Avoid including lodash iteratee in builds (saves 60kb :feelsgood:)lodash-use

1 files changed, 5063 insertions, 6702 deletions

diff --git a/dist/async.js b/dist/async.js
index e5efdba..b964a50 100644
--- a/dist/async.js
+++ b/dist/async.js
@@ -1,6823 +1,5184 @@
 (function (global, factory) {
-    typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
-    typeof define === 'function' && define.amd ? define(['exports'], factory) :
-    (factory((global.async = global.async || {})));
+  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
+  typeof define === 'function' && define.amd ? define(['exports'], factory) :
+  (factory((global.async = global.async || {})));
 }(this, function (exports) { 'use strict';
 
-    /**
-     * A faster alternative to `Function#apply`, this function invokes `func`
-     * with the `this` binding of `thisArg` and the arguments of `args`.
-     *
-     * @private
-     * @param {Function} func The function to invoke.
-     * @param {*} thisArg The `this` binding of `func`.
-     * @param {Array} args The arguments to invoke `func` with.
-     * @returns {*} Returns the result of `func`.
-     */
-    function apply(func, thisArg, args) {
-      var length = args.length;
-      switch (length) {
-        case 0: return func.call(thisArg);
-        case 1: return func.call(thisArg, args[0]);
-        case 2: return func.call(thisArg, args[0], args[1]);
-        case 3: return func.call(thisArg, args[0], args[1], args[2]);
-      }
-      return func.apply(thisArg, args);
-    }
-
-    /**
-     * Checks if `value` is the
-     * [language type](http://www.ecma-international.org/ecma-262/6.0/#sec-ecmascript-language-types)
-     * of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
-     *
-     * @static
-     * @memberOf _
-     * @since 0.1.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is an object, else `false`.
-     * @example
-     *
-     * _.isObject({});
-     * // => true
-     *
-     * _.isObject([1, 2, 3]);
-     * // => true
-     *
-     * _.isObject(_.noop);
-     * // => true
-     *
-     * _.isObject(null);
-     * // => false
-     */
-    function isObject(value) {
-      var type = typeof value;
-      return !!value && (type == 'object' || type == 'function');
-    }
-
-    var funcTag = '[object Function]';
-    var genTag = '[object GeneratorFunction]';
-    /** Used for built-in method references. */
-    var objectProto = Object.prototype;
-
-    /**
-     * Used to resolve the
-     * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
-     * of values.
-     */
-    var objectToString = objectProto.toString;
-
-    /**
-     * Checks if `value` is classified as a `Function` object.
-     *
-     * @static
-     * @memberOf _
-     * @since 0.1.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is correctly classified,
-     *  else `false`.
-     * @example
-     *
-     * _.isFunction(_);
-     * // => true
-     *
-     * _.isFunction(/abc/);
-     * // => false
-     */
-    function isFunction(value) {
-      // The use of `Object#toString` avoids issues with the `typeof` operator
-      // in Safari 8 which returns 'object' for typed array and weak map constructors,
-      // and PhantomJS 1.9 which returns 'function' for `NodeList` instances.
-      var tag = isObject(value) ? objectToString.call(value) : '';
-      return tag == funcTag || tag == genTag;
-    }
-
-    /**
-     * Checks if `value` is object-like. A value is object-like if it's not `null`
-     * and has a `typeof` result of "object".
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is object-like, else `false`.
-     * @example
-     *
-     * _.isObjectLike({});
-     * // => true
-     *
-     * _.isObjectLike([1, 2, 3]);
-     * // => true
-     *
-     * _.isObjectLike(_.noop);
-     * // => false
-     *
-     * _.isObjectLike(null);
-     * // => false
-     */
-    function isObjectLike(value) {
-      return !!value && typeof value == 'object';
-    }
-
-    /** `Object#toString` result references. */
-    var symbolTag = '[object Symbol]';
-
-    /** Used for built-in method references. */
-    var objectProto$1 = Object.prototype;
-
-    /**
-     * Used to resolve the
-     * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
-     * of values.
-     */
-    var objectToString$1 = objectProto$1.toString;
-
-    /**
-     * Checks if `value` is classified as a `Symbol` primitive or object.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is correctly classified,
-     *  else `false`.
-     * @example
-     *
-     * _.isSymbol(Symbol.iterator);
-     * // => true
-     *
-     * _.isSymbol('abc');
-     * // => false
-     */
-    function isSymbol(value) {
-      return typeof value == 'symbol' ||
-        (isObjectLike(value) && objectToString$1.call(value) == symbolTag);
+  /**
+   * A faster alternative to `Function#apply`, this function invokes `func`
+   * with the `this` binding of `thisArg` and the arguments of `args`.
+   *
+   * @private
+   * @param {Function} func The function to invoke.
+   * @param {*} thisArg The `this` binding of `func`.
+   * @param {Array} args The arguments to invoke `func` with.
+   * @returns {*} Returns the result of `func`.
+   */
+  function apply(func, thisArg, args) {
+    var length = args.length;
+    switch (length) {
+      case 0: return func.call(thisArg);
+      case 1: return func.call(thisArg, args[0]);
+      case 2: return func.call(thisArg, args[0], args[1]);
+      case 3: return func.call(thisArg, args[0], args[1], args[2]);
+    }
+    return func.apply(thisArg, args);
+  }
+
+  /**
+   * Checks if `value` is the
+   * [language type](http://www.ecma-international.org/ecma-262/6.0/#sec-ecmascript-language-types)
+   * of `Object`. (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
+   *
+   * @static
+   * @memberOf _
+   * @since 0.1.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is an object, else `false`.
+   * @example
+   *
+   * _.isObject({});
+   * // => true
+   *
+   * _.isObject([1, 2, 3]);
+   * // => true
+   *
+   * _.isObject(_.noop);
+   * // => true
+   *
+   * _.isObject(null);
+   * // => false
+   */
+  function isObject(value) {
+    var type = typeof value;
+    return !!value && (type == 'object' || type == 'function');
+  }
+
+  var funcTag = '[object Function]';
+  var genTag = '[object GeneratorFunction]';
+  /** Used for built-in method references. */
+  var objectProto = Object.prototype;
+
+  /**
+   * Used to resolve the
+   * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
+   * of values.
+   */
+  var objectToString = objectProto.toString;
+
+  /**
+   * Checks if `value` is classified as a `Function` object.
+   *
+   * @static
+   * @memberOf _
+   * @since 0.1.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is correctly classified,
+   *  else `false`.
+   * @example
+   *
+   * _.isFunction(_);
+   * // => true
+   *
+   * _.isFunction(/abc/);
+   * // => false
+   */
+  function isFunction(value) {
+    // The use of `Object#toString` avoids issues with the `typeof` operator
+    // in Safari 8 which returns 'object' for typed array and weak map constructors,
+    // and PhantomJS 1.9 which returns 'function' for `NodeList` instances.
+    var tag = isObject(value) ? objectToString.call(value) : '';
+    return tag == funcTag || tag == genTag;
+  }
+
+  /**
+   * Checks if `value` is object-like. A value is object-like if it's not `null`
+   * and has a `typeof` result of "object".
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is object-like, else `false`.
+   * @example
+   *
+   * _.isObjectLike({});
+   * // => true
+   *
+   * _.isObjectLike([1, 2, 3]);
+   * // => true
+   *
+   * _.isObjectLike(_.noop);
+   * // => false
+   *
+   * _.isObjectLike(null);
+   * // => false
+   */
+  function isObjectLike(value) {
+    return !!value && typeof value == 'object';
+  }
+
+  /** `Object#toString` result references. */
+  var symbolTag = '[object Symbol]';
+
+  /** Used for built-in method references. */
+  var objectProto$1 = Object.prototype;
+
+  /**
+   * Used to resolve the
+   * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
+   * of values.
+   */
+  var objectToString$1 = objectProto$1.toString;
+
+  /**
+   * Checks if `value` is classified as a `Symbol` primitive or object.
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is correctly classified,
+   *  else `false`.
+   * @example
+   *
+   * _.isSymbol(Symbol.iterator);
+   * // => true
+   *
+   * _.isSymbol('abc');
+   * // => false
+   */
+  function isSymbol(value) {
+    return typeof value == 'symbol' ||
+      (isObjectLike(value) && objectToString$1.call(value) == symbolTag);
+  }
+
+  /** Used as references for various `Number` constants. */
+  var NAN = 0 / 0;
+
+  /** Used to match leading and trailing whitespace. */
+  var reTrim = /^\s+|\s+$/g;
+
+  /** Used to detect bad signed hexadecimal string values. */
+  var reIsBadHex = /^[-+]0x[0-9a-f]+$/i;
+
+  /** Used to detect binary string values. */
+  var reIsBinary = /^0b[01]+$/i;
+
+  /** Used to detect octal string values. */
+  var reIsOctal = /^0o[0-7]+$/i;
+
+  /** Built-in method references without a dependency on `root`. */
+  var freeParseInt = parseInt;
+
+  /**
+   * Converts `value` to a number.
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to process.
+   * @returns {number} Returns the number.
+   * @example
+   *
+   * _.toNumber(3.2);
+   * // => 3.2
+   *
+   * _.toNumber(Number.MIN_VALUE);
+   * // => 5e-324
+   *
+   * _.toNumber(Infinity);
+   * // => Infinity
+   *
+   * _.toNumber('3.2');
+   * // => 3.2
+   */
+  function toNumber(value) {
+    if (typeof value == 'number') {
+      return value;
     }
+    if (isSymbol(value)) {
+      return NAN;
+    }
+    if (isObject(value)) {
+      var other = isFunction(value.valueOf) ? value.valueOf() : value;
+      value = isObject(other) ? (other + '') : other;
+    }
+    if (typeof value != 'string') {
+      return value === 0 ? value : +value;
+    }
+    value = value.replace(reTrim, '');
+    var isBinary = reIsBinary.test(value);
+    return (isBinary || reIsOctal.test(value))
+      ? freeParseInt(value.slice(2), isBinary ? 2 : 8)
+      : (reIsBadHex.test(value) ? NAN : +value);
+  }
+
+  var INFINITY = 1 / 0;
+  var MAX_INTEGER = 1.7976931348623157e+308;
+  /**
+   * Converts `value` to a finite number.
+   *
+   * @static
+   * @memberOf _
+   * @since 4.12.0
+   * @category Lang
+   * @param {*} value The value to convert.
+   * @returns {number} Returns the converted number.
+   * @example
+   *
+   * _.toFinite(3.2);
+   * // => 3.2
+   *
+   * _.toFinite(Number.MIN_VALUE);
+   * // => 5e-324
+   *
+   * _.toFinite(Infinity);
+   * // => 1.7976931348623157e+308
+   *
+   * _.toFinite('3.2');
+   * // => 3.2
+   */
+  function toFinite(value) {
+    if (!value) {
+      return value === 0 ? value : 0;
+    }
+    value = toNumber(value);
+    if (value === INFINITY || value === -INFINITY) {
+      var sign = (value < 0 ? -1 : 1);
+      return sign * MAX_INTEGER;
+    }
+    return value === value ? value : 0;
+  }
+
+  /**
+   * Converts `value` to an integer.
+   *
+   * **Note:** This method is loosely based on
+   * [`ToInteger`](http://www.ecma-international.org/ecma-262/6.0/#sec-tointeger).
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to convert.
+   * @returns {number} Returns the converted integer.
+   * @example
+   *
+   * _.toInteger(3.2);
+   * // => 3
+   *
+   * _.toInteger(Number.MIN_VALUE);
+   * // => 0
+   *
+   * _.toInteger(Infinity);
+   * // => 1.7976931348623157e+308
+   *
+   * _.toInteger('3.2');
+   * // => 3
+   */
+  function toInteger(value) {
+    var result = toFinite(value),
+        remainder = result % 1;
+
+    return result === result ? (remainder ? result - remainder : result) : 0;
+  }
+
+  /** Used as the `TypeError` message for "Functions" methods. */
+  var FUNC_ERROR_TEXT = 'Expected a function';
+
+  /* Built-in method references for those with the same name as other `lodash` methods. */
+  var nativeMax = Math.max;
+
+  /**
+   * Creates a function that invokes `func` with the `this` binding of the
+   * created function and arguments from `start` and beyond provided as
+   * an array.
+   *
+   * **Note:** This method is based on the
+   * [rest parameter](https://mdn.io/rest_parameters).
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Function
+   * @param {Function} func The function to apply a rest parameter to.
+   * @param {number} [start=func.length-1] The start position of the rest parameter.
+   * @returns {Function} Returns the new function.
+   * @example
+   *
+   * var say = _.rest(function(what, names) {
+   *   return what + ' ' + _.initial(names).join(', ') +
+   *     (_.size(names) > 1 ? ', & ' : '') + _.last(names);
+   * });
+   *
+   * say('hello', 'fred', 'barney', 'pebbles');
+   * // => 'hello fred, barney, & pebbles'
+   */
+  function rest(func, start) {
+    if (typeof func != 'function') {
+      throw new TypeError(FUNC_ERROR_TEXT);
+    }
+    start = nativeMax(start === undefined ? (func.length - 1) : toInteger(start), 0);
+    return function() {
+      var args = arguments,
+          index = -1,
+          length = nativeMax(args.length - start, 0),
+          array = Array(length);
 
-    /** Used as references for various `Number` constants. */
-    var NAN = 0 / 0;
-
-    /** Used to match leading and trailing whitespace. */
-    var reTrim = /^\s+|\s+$/g;
-
-    /** Used to detect bad signed hexadecimal string values. */
-    var reIsBadHex = /^[-+]0x[0-9a-f]+$/i;
-
-    /** Used to detect binary string values. */
-    var reIsBinary = /^0b[01]+$/i;
-
-    /** Used to detect octal string values. */
-    var reIsOctal = /^0o[0-7]+$/i;
-
-    /** Built-in method references without a dependency on `root`. */
-    var freeParseInt = parseInt;
-
-    /**
-     * Converts `value` to a number.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to process.
-     * @returns {number} Returns the number.
-     * @example
-     *
-     * _.toNumber(3.2);
-     * // => 3.2
-     *
-     * _.toNumber(Number.MIN_VALUE);
-     * // => 5e-324
-     *
-     * _.toNumber(Infinity);
-     * // => Infinity
-     *
-     * _.toNumber('3.2');
-     * // => 3.2
-     */
-    function toNumber(value) {
-      if (typeof value == 'number') {
-        return value;
-      }
-      if (isSymbol(value)) {
-        return NAN;
+      while (++index < length) {
+        array[index] = args[start + index];
       }
-      if (isObject(value)) {
-        var other = isFunction(value.valueOf) ? value.valueOf() : value;
-        value = isObject(other) ? (other + '') : other;
+      switch (start) {
+        case 0: return func.call(this, array);
+        case 1: return func.call(this, args[0], array);
+        case 2: return func.call(this, args[0], args[1], array);
       }
-      if (typeof value != 'string') {
-        return value === 0 ? value : +value;
+      var otherArgs = Array(start + 1);
+      index = -1;
+      while (++index < start) {
+        otherArgs[index] = args[index];
       }
-      value = value.replace(reTrim, '');
-      var isBinary = reIsBinary.test(value);
-      return (isBinary || reIsOctal.test(value))
-        ? freeParseInt(value.slice(2), isBinary ? 2 : 8)
-        : (reIsBadHex.test(value) ? NAN : +value);
-    }
-
-    var INFINITY = 1 / 0;
-    var MAX_INTEGER = 1.7976931348623157e+308;
-    /**
-     * Converts `value` to a finite number.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.12.0
-     * @category Lang
-     * @param {*} value The value to convert.
-     * @returns {number} Returns the converted number.
-     * @example
-     *
-     * _.toFinite(3.2);
-     * // => 3.2
-     *
-     * _.toFinite(Number.MIN_VALUE);
-     * // => 5e-324
-     *
-     * _.toFinite(Infinity);
-     * // => 1.7976931348623157e+308
-     *
-     * _.toFinite('3.2');
-     * // => 3.2
-     */
-    function toFinite(value) {
-      if (!value) {
-        return value === 0 ? value : 0;
-      }
-      value = toNumber(value);
-      if (value === INFINITY || value === -INFINITY) {
-        var sign = (value < 0 ? -1 : 1);
-        return sign * MAX_INTEGER;
-      }
-      return value === value ? value : 0;
-    }
-
-    /**
-     * Converts `value` to an integer.
-     *
-     * **Note:** This method is loosely based on
-     * [`ToInteger`](http://www.ecma-international.org/ecma-262/6.0/#sec-tointeger).
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to convert.
-     * @returns {number} Returns the converted integer.
-     * @example
-     *
-     * _.toInteger(3.2);
-     * // => 3
-     *
-     * _.toInteger(Number.MIN_VALUE);
-     * // => 0
-     *
-     * _.toInteger(Infinity);
-     * // => 1.7976931348623157e+308
-     *
-     * _.toInteger('3.2');
-     * // => 3
-     */
-    function toInteger(value) {
-      var result = toFinite(value),
-          remainder = result % 1;
-
-      return result === result ? (remainder ? result - remainder : result) : 0;
-    }
-
-    /** Used as the `TypeError` message for "Functions" methods. */
-    var FUNC_ERROR_TEXT = 'Expected a function';
-
-    /* Built-in method references for those with the same name as other `lodash` methods. */
-    var nativeMax = Math.max;
-
-    /**
-     * Creates a function that invokes `func` with the `this` binding of the
-     * created function and arguments from `start` and beyond provided as
-     * an array.
-     *
-     * **Note:** This method is based on the
-     * [rest parameter](https://mdn.io/rest_parameters).
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Function
-     * @param {Function} func The function to apply a rest parameter to.
-     * @param {number} [start=func.length-1] The start position of the rest parameter.
-     * @returns {Function} Returns the new function.
-     * @example
-     *
-     * var say = _.rest(function(what, names) {
-     *   return what + ' ' + _.initial(names).join(', ') +
-     *     (_.size(names) > 1 ? ', & ' : '') + _.last(names);
-     * });
-     *
-     * say('hello', 'fred', 'barney', 'pebbles');
-     * // => 'hello fred, barney, & pebbles'
-     */
-    function rest(func, start) {
-      if (typeof func != 'function') {
-        throw new TypeError(FUNC_ERROR_TEXT);
-      }
-      start = nativeMax(start === undefined ? (func.length - 1) : toInteger(start), 0);
-      return function() {
-        var args = arguments,
-            index = -1,
-            length = nativeMax(args.length - start, 0),
-            array = Array(length);
-
-        while (++index < length) {
-          array[index] = args[start + index];
-        }
-        switch (start) {
-          case 0: return func.call(this, array);
-          case 1: return func.call(this, args[0], array);
-          case 2: return func.call(this, args[0], args[1], array);
-        }
-        var otherArgs = Array(start + 1);
-        index = -1;
-        while (++index < start) {
-          otherArgs[index] = args[index];
-        }
-        otherArgs[start] = array;
-        return apply(func, this, otherArgs);
-      };
-    }
-
-    function initialParams (fn) {
-        return rest(function (args /*..., callback*/) {
-            var callback = args.pop();
-            fn.call(this, args, callback);
-        });
-    }
-
-    function applyEach$1(eachfn) {
-        return rest(function (fns, args) {
-            var go = initialParams(function (args, callback) {
-                var that = this;
-                return eachfn(fns, function (fn, cb) {
-                    fn.apply(that, args.concat([cb]));
-                }, callback);
-            });
-            if (args.length) {
-                return go.apply(this, args);
-            } else {
-                return go;
-            }
-        });
-    }
-
-    /**
-     * A method that returns `undefined`.
-     *
-     * @static
-     * @memberOf _
-     * @since 2.3.0
-     * @category Util
-     * @example
-     *
-     * _.times(2, _.noop);
-     * // => [undefined, undefined]
-     */
-    function noop() {
-      // No operation performed.
-    }
-
-    function once(fn) {
-        return function () {
-            if (fn === null) return;
-            var callFn = fn;
-            fn = null;
-            callFn.apply(this, arguments);
-        };
-    }
+      otherArgs[start] = array;
+      return apply(func, this, otherArgs);
+    };
+  }
 
-    /**
-     * The base implementation of `_.property` without support for deep paths.
-     *
-     * @private
-     * @param {string} key The key of the property to get.
-     * @returns {Function} Returns the new accessor function.
-     */
-    function baseProperty(key) {
-      return function(object) {
-        return object == null ? undefined : object[key];
+  function initialParams (fn) {
+      return rest(function (args /*..., callback*/) {
+          var callback = args.pop();
+          fn.call(this, args, callback);
+      });
+  }
+
+  function applyEach$1(eachfn) {
+      return rest(function (fns, args) {
+          var go = initialParams(function (args, callback) {
+              var that = this;
+              return eachfn(fns, function (fn, cb) {
+                  fn.apply(that, args.concat([cb]));
+              }, callback);
+          });
+          if (args.length) {
+              return go.apply(this, args);
+          } else {
+              return go;
+          }
+      });
+  }
+
+  /**
+   * A method that returns `undefined`.
+   *
+   * @static
+   * @memberOf _
+   * @since 2.3.0
+   * @category Util
+   * @example
+   *
+   * _.times(2, _.noop);
+   * // => [undefined, undefined]
+   */
+  function noop() {
+    // No operation performed.
+  }
+
+  function once(fn) {
+      return function () {
+          if (fn === null) return;
+          var callFn = fn;
+          fn = null;
+          callFn.apply(this, arguments);
       };
-    }
-
-    /**
-     * Gets the "length" property value of `object`.
-     *
-     * **Note:** This function is used to avoid a
-     * [JIT bug](https://bugs.webkit.org/show_bug.cgi?id=142792) that affects
-     * Safari on at least iOS 8.1-8.3 ARM64.
-     *
-     * @private
-     * @param {Object} object The object to query.
-     * @returns {*} Returns the "length" value.
-     */
-    var getLength = baseProperty('length');
-
-    /** Used as references for various `Number` constants. */
-    var MAX_SAFE_INTEGER = 9007199254740991;
-
-    /**
-     * Checks if `value` is a valid array-like length.
-     *
-     * **Note:** This function is loosely based on
-     * [`ToLength`](http://ecma-international.org/ecma-262/6.0/#sec-tolength).
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is a valid length,
-     *  else `false`.
-     * @example
-     *
-     * _.isLength(3);
-     * // => true
-     *
-     * _.isLength(Number.MIN_VALUE);
-     * // => false
-     *
-     * _.isLength(Infinity);
-     * // => false
-     *
-     * _.isLength('3');
-     * // => false
-     */
-    function isLength(value) {
-      return typeof value == 'number' &&
-        value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;
-    }
-
-    /**
-     * Checks if `value` is array-like. A value is considered array-like if it's
-     * not a function and has a `value.length` that's an integer greater than or
-     * equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
-     * @example
-     *
-     * _.isArrayLike([1, 2, 3]);
-     * // => true
-     *
-     * _.isArrayLike(document.body.children);
-     * // => true
-     *
-     * _.isArrayLike('abc');
-     * // => true
-     *
-     * _.isArrayLike(_.noop);
-     * // => false
-     */
-    function isArrayLike(value) {
-      return value != null && isLength(getLength(value)) && !isFunction(value);
-    }
-
-    var iteratorSymbol = typeof Symbol === 'function' && Symbol.iterator;
-
-    function getIterator (coll) {
-        return iteratorSymbol && coll[iteratorSymbol] && coll[iteratorSymbol]();
-    }
-
-    /* Built-in method references for those with the same name as other `lodash` methods. */
-    var nativeGetPrototype = Object.getPrototypeOf;
-
-    /**
-     * Gets the `[[Prototype]]` of `value`.
-     *
-     * @private
-     * @param {*} value The value to query.
-     * @returns {null|Object} Returns the `[[Prototype]]`.
-     */
-    function getPrototype(value) {
-      return nativeGetPrototype(Object(value));
-    }
-
-    /** Used for built-in method references. */
-    var objectProto$2 = Object.prototype;
-
-    /** Used to check objects for own properties. */
-    var hasOwnProperty = objectProto$2.hasOwnProperty;
-
-    /**
-     * The base implementation of `_.has` without support for deep paths.
-     *
-     * @private
-     * @param {Object} [object] The object to query.
-     * @param {Array|string} key The key to check.
-     * @returns {boolean} Returns `true` if `key` exists, else `false`.
-     */
-    function baseHas(object, key) {
-      // Avoid a bug in IE 10-11 where objects with a [[Prototype]] of `null`,
-      // that are composed entirely of index properties, return `false` for
-      // `hasOwnProperty` checks of them.
-      return object != null &&
-        (hasOwnProperty.call(object, key) ||
-          (typeof object == 'object' && key in object && getPrototype(object) === null));
-    }
-
-    /* Built-in method references for those with the same name as other `lodash` methods. */
-    var nativeKeys = Object.keys;
-
-    /**
-     * The base implementation of `_.keys` which doesn't skip the constructor
-     * property of prototypes or treat sparse arrays as dense.
-     *
-     * @private
-     * @param {Object} object The object to query.
-     * @returns {Array} Returns the array of property names.
-     */
-    function baseKeys(object) {
-      return nativeKeys(Object(object));
-    }
-
-    /**
-     * The base implementation of `_.times` without support for iteratee shorthands
-     * or max array length checks.
-     *
-     * @private
-     * @param {number} n The number of times to invoke `iteratee`.
-     * @param {Function} iteratee The function invoked per iteration.
-     * @returns {Array} Returns the array of results.
-     */
-    function baseTimes(n, iteratee) {
-      var index = -1,
-          result = Array(n);
-
-      while (++index < n) {
-        result[index] = iteratee(index);
-      }
-      return result;
-    }
-
-    /**
-     * This method is like `_.isArrayLike` except that it also checks if `value`
-     * is an object.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is an array-like object,
-     *  else `false`.
-     * @example
-     *
-     * _.isArrayLikeObject([1, 2, 3]);
-     * // => true
-     *
-     * _.isArrayLikeObject(document.body.children);
-     * // => true
-     *
-     * _.isArrayLikeObject('abc');
-     * // => false
-     *
-     * _.isArrayLikeObject(_.noop);
-     * // => false
-     */
-    function isArrayLikeObject(value) {
-      return isObjectLike(value) && isArrayLike(value);
-    }
-
-    /** `Object#toString` result references. */
-    var argsTag = '[object Arguments]';
-
-    /** Used for built-in method references. */
-    var objectProto$3 = Object.prototype;
-
-    /** Used to check objects for own properties. */
-    var hasOwnProperty$1 = objectProto$3.hasOwnProperty;
-
-    /**
-     * Used to resolve the
-     * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
-     * of values.
-     */
-    var objectToString$2 = objectProto$3.toString;
-
-    /** Built-in value references. */
-    var propertyIsEnumerable = objectProto$3.propertyIsEnumerable;
-
-    /**
-     * Checks if `value` is likely an `arguments` object.
-     *
-     * @static
-     * @memberOf _
-     * @since 0.1.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is correctly classified,
-     *  else `false`.
-     * @example
-     *
-     * _.isArguments(function() { return arguments; }());
-     * // => true
-     *
-     * _.isArguments([1, 2, 3]);
-     * // => false
-     */
-    function isArguments(value) {
-      // Safari 8.1 incorrectly makes `arguments.callee` enumerable in strict mode.
-      return isArrayLikeObject(value) && hasOwnProperty$1.call(value, 'callee') &&
-        (!propertyIsEnumerable.call(value, 'callee') || objectToString$2.call(value) == argsTag);
-    }
-
-    /**
-     * Checks if `value` is classified as an `Array` object.
-     *
-     * @static
-     * @memberOf _
-     * @since 0.1.0
-     * @type {Function}
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is correctly classified,
-     *  else `false`.
-     * @example
-     *
-     * _.isArray([1, 2, 3]);
-     * // => true
-     *
-     * _.isArray(document.body.children);
-     * // => false
-     *
-     * _.isArray('abc');
-     * // => false
-     *
-     * _.isArray(_.noop);
-     * // => false
-     */
-    var isArray = Array.isArray;
-
-    /** `Object#toString` result references. */
-    var stringTag = '[object String]';
-
-    /** Used for built-in method references. */
-    var objectProto$4 = Object.prototype;
-
-    /**
-     * Used to resolve the
-     * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
-     * of values.
-     */
-    var objectToString$3 = objectProto$4.toString;
-
-    /**
-     * Checks if `value` is classified as a `String` primitive or object.
-     *
-     * @static
-     * @since 0.1.0
-     * @memberOf _
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is correctly classified,
-     *  else `false`.
-     * @example
-     *
-     * _.isString('abc');
-     * // => true
-     *
-     * _.isString(1);
-     * // => false
-     */
-    function isString(value) {
-      return typeof value == 'string' ||
-        (!isArray(value) && isObjectLike(value) && objectToString$3.call(value) == stringTag);
-    }
-
-    /**
-     * Creates an array of index keys for `object` values of arrays,
-     * `arguments` objects, and strings, otherwise `null` is returned.
-     *
-     * @private
-     * @param {Object} object The object to query.
-     * @returns {Array|null} Returns index keys, else `null`.
-     */
-    function indexKeys(object) {
-      var length = object ? object.length : undefined;
-      if (isLength(length) &&
-          (isArray(object) || isString(object) || isArguments(object))) {
-        return baseTimes(length, String);
+  }
+
+  /**
+   * The base implementation of `_.property` without support for deep paths.
+   *
+   * @private
+   * @param {string} key The key of the property to get.
+   * @returns {Function} Returns the new accessor function.
+   */
+  function baseProperty(key) {
+    return function(object) {
+      return object == null ? undefined : object[key];
+    };
+  }
+
+  /**
+   * Gets the "length" property value of `object`.
+   *
+   * **Note:** This function is used to avoid a
+   * [JIT bug](https://bugs.webkit.org/show_bug.cgi?id=142792) that affects
+   * Safari on at least iOS 8.1-8.3 ARM64.
+   *
+   * @private
+   * @param {Object} object The object to query.
+   * @returns {*} Returns the "length" value.
+   */
+  var getLength = baseProperty('length');
+
+  /** Used as references for various `Number` constants. */
+  var MAX_SAFE_INTEGER = 9007199254740991;
+
+  /**
+   * Checks if `value` is a valid array-like length.
+   *
+   * **Note:** This function is loosely based on
+   * [`ToLength`](http://ecma-international.org/ecma-262/6.0/#sec-tolength).
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is a valid length,
+   *  else `false`.
+   * @example
+   *
+   * _.isLength(3);
+   * // => true
+   *
+   * _.isLength(Number.MIN_VALUE);
+   * // => false
+   *
+   * _.isLength(Infinity);
+   * // => false
+   *
+   * _.isLength('3');
+   * // => false
+   */
+  function isLength(value) {
+    return typeof value == 'number' &&
+      value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;
+  }
+
+  /**
+   * Checks if `value` is array-like. A value is considered array-like if it's
+   * not a function and has a `value.length` that's an integer greater than or
+   * equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
+   * @example
+   *
+   * _.isArrayLike([1, 2, 3]);
+   * // => true
+   *
+   * _.isArrayLike(document.body.children);
+   * // => true
+   *
+   * _.isArrayLike('abc');
+   * // => true
+   *
+   * _.isArrayLike(_.noop);
+   * // => false
+   */
+  function isArrayLike(value) {
+    return value != null && isLength(getLength(value)) && !isFunction(value);
+  }
+
+  var iteratorSymbol = typeof Symbol === 'function' && Symbol.iterator;
+
+  function getIterator (coll) {
+      return iteratorSymbol && coll[iteratorSymbol] && coll[iteratorSymbol]();
+  }
+
+  /* Built-in method references for those with the same name as other `lodash` methods. */
+  var nativeGetPrototype = Object.getPrototypeOf;
+
+  /**
+   * Gets the `[[Prototype]]` of `value`.
+   *
+   * @private
+   * @param {*} value The value to query.
+   * @returns {null|Object} Returns the `[[Prototype]]`.
+   */
+  function getPrototype(value) {
+    return nativeGetPrototype(Object(value));
+  }
+
+  /** Used for built-in method references. */
+  var objectProto$2 = Object.prototype;
+
+  /** Used to check objects for own properties. */
+  var hasOwnProperty = objectProto$2.hasOwnProperty;
+
+  /**
+   * The base implementation of `_.has` without support for deep paths.
+   *
+   * @private
+   * @param {Object} [object] The object to query.
+   * @param {Array|string} key The key to check.
+   * @returns {boolean} Returns `true` if `key` exists, else `false`.
+   */
+  function baseHas(object, key) {
+    // Avoid a bug in IE 10-11 where objects with a [[Prototype]] of `null`,
+    // that are composed entirely of index properties, return `false` for
+    // `hasOwnProperty` checks of them.
+    return object != null &&
+      (hasOwnProperty.call(object, key) ||
+        (typeof object == 'object' && key in object && getPrototype(object) === null));
+  }
+
+  /* Built-in method references for those with the same name as other `lodash` methods. */
+  var nativeKeys = Object.keys;
+
+  /**
+   * The base implementation of `_.keys` which doesn't skip the constructor
+   * property of prototypes or treat sparse arrays as dense.
+   *
+   * @private
+   * @param {Object} object The object to query.
+   * @returns {Array} Returns the array of property names.
+   */
+  function baseKeys(object) {
+    return nativeKeys(Object(object));
+  }
+
+  /**
+   * The base implementation of `_.times` without support for iteratee shorthands
+   * or max array length checks.
+   *
+   * @private
+   * @param {number} n The number of times to invoke `iteratee`.
+   * @param {Function} iteratee The function invoked per iteration.
+   * @returns {Array} Returns the array of results.
+   */
+  function baseTimes(n, iteratee) {
+    var index = -1,
+        result = Array(n);
+
+    while (++index < n) {
+      result[index] = iteratee(index);
+    }
+    return result;
+  }
+
+  /**
+   * This method is like `_.isArrayLike` except that it also checks if `value`
+   * is an object.
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is an array-like object,
+   *  else `false`.
+   * @example
+   *
+   * _.isArrayLikeObject([1, 2, 3]);
+   * // => true
+   *
+   * _.isArrayLikeObject(document.body.children);
+   * // => true
+   *
+   * _.isArrayLikeObject('abc');
+   * // => false
+   *
+   * _.isArrayLikeObject(_.noop);
+   * // => false
+   */
+  function isArrayLikeObject(value) {
+    return isObjectLike(value) && isArrayLike(value);
+  }
+
+  /** `Object#toString` result references. */
+  var argsTag = '[object Arguments]';
+
+  /** Used for built-in method references. */
+  var objectProto$3 = Object.prototype;
+
+  /** Used to check objects for own properties. */
+  var hasOwnProperty$1 = objectProto$3.hasOwnProperty;
+
+  /**
+   * Used to resolve the
+   * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
+   * of values.
+   */
+  var objectToString$2 = objectProto$3.toString;
+
+  /** Built-in value references. */
+  var propertyIsEnumerable = objectProto$3.propertyIsEnumerable;
+
+  /**
+   * Checks if `value` is likely an `arguments` object.
+   *
+   * @static
+   * @memberOf _
+   * @since 0.1.0
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is correctly classified,
+   *  else `false`.
+   * @example
+   *
+   * _.isArguments(function() { return arguments; }());
+   * // => true
+   *
+   * _.isArguments([1, 2, 3]);
+   * // => false
+   */
+  function isArguments(value) {
+    // Safari 8.1 incorrectly makes `arguments.callee` enumerable in strict mode.
+    return isArrayLikeObject(value) && hasOwnProperty$1.call(value, 'callee') &&
+      (!propertyIsEnumerable.call(value, 'callee') || objectToString$2.call(value) == argsTag);
+  }
+
+  /**
+   * Checks if `value` is classified as an `Array` object.
+   *
+   * @static
+   * @memberOf _
+   * @since 0.1.0
+   * @type {Function}
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is correctly classified,
+   *  else `false`.
+   * @example
+   *
+   * _.isArray([1, 2, 3]);
+   * // => true
+   *
+   * _.isArray(document.body.children);
+   * // => false
+   *
+   * _.isArray('abc');
+   * // => false
+   *
+   * _.isArray(_.noop);
+   * // => false
+   */
+  var isArray = Array.isArray;
+
+  /** `Object#toString` result references. */
+  var stringTag = '[object String]';
+
+  /** Used for built-in method references. */
+  var objectProto$4 = Object.prototype;
+
+  /**
+   * Used to resolve the
+   * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
+   * of values.
+   */
+  var objectToString$3 = objectProto$4.toString;
+
+  /**
+   * Checks if `value` is classified as a `String` primitive or object.
+   *
+   * @static
+   * @since 0.1.0
+   * @memberOf _
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is correctly classified,
+   *  else `false`.
+   * @example
+   *
+   * _.isString('abc');
+   * // => true
+   *
+   * _.isString(1);
+   * // => false
+   */
+  function isString(value) {
+    return typeof value == 'string' ||
+      (!isArray(value) && isObjectLike(value) && objectToString$3.call(value) == stringTag);
+  }
+
+  /**
+   * Creates an array of index keys for `object` values of arrays,
+   * `arguments` objects, and strings, otherwise `null` is returned.
+   *
+   * @private
+   * @param {Object} object The object to query.
+   * @returns {Array|null} Returns index keys, else `null`.
+   */
+  function indexKeys(object) {
+    var length = object ? object.length : undefined;
+    if (isLength(length) &&
+        (isArray(object) || isString(object) || isArguments(object))) {
+      return baseTimes(length, String);
+    }
+    return null;
+  }
+
+  /** Used as references for various `Number` constants. */
+  var MAX_SAFE_INTEGER$1 = 9007199254740991;
+
+  /** Used to detect unsigned integer values. */
+  var reIsUint = /^(?:0|[1-9]\d*)$/;
+
+  /**
+   * Checks if `value` is a valid array-like index.
+   *
+   * @private
+   * @param {*} value The value to check.
+   * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
+   * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
+   */
+  function isIndex(value, length) {
+    length = length == null ? MAX_SAFE_INTEGER$1 : length;
+    return !!length &&
+      (typeof value == 'number' || reIsUint.test(value)) &&
+      (value > -1 && value % 1 == 0 && value < length);
+  }
+
+  /** Used for built-in method references. */
+  var objectProto$5 = Object.prototype;
+
+  /**
+   * Checks if `value` is likely a prototype object.
+   *
+   * @private
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is a prototype, else `false`.
+   */
+  function isPrototype(value) {
+    var Ctor = value && value.constructor,
+        proto = (typeof Ctor == 'function' && Ctor.prototype) || objectProto$5;
+
+    return value === proto;
+  }
+
+  /**
+   * Creates an array of the own enumerable property names of `object`.
+   *
+   * **Note:** Non-object values are coerced to objects. See the
+   * [ES spec](http://ecma-international.org/ecma-262/6.0/#sec-object.keys)
+   * for more details.
+   *
+   * @static
+   * @since 0.1.0
+   * @memberOf _
+   * @category Object
+   * @param {Object} object The object to query.
+   * @returns {Array} Returns the array of property names.
+   * @example
+   *
+   * function Foo() {
+   *   this.a = 1;
+   *   this.b = 2;
+   * }
+   *
+   * Foo.prototype.c = 3;
+   *
+   * _.keys(new Foo);
+   * // => ['a', 'b'] (iteration order is not guaranteed)
+   *
+   * _.keys('hi');
+   * // => ['0', '1']
+   */
+  function keys(object) {
+    var isProto = isPrototype(object);
+    if (!(isProto || isArrayLike(object))) {
+      return baseKeys(object);
+    }
+    var indexes = indexKeys(object),
+        skipIndexes = !!indexes,
+        result = indexes || [],
+        length = result.length;
+
+    for (var key in object) {
+      if (baseHas(object, key) &&
+          !(skipIndexes && (key == 'length' || isIndex(key, length))) &&
+          !(isProto && key == 'constructor')) {
+        result.push(key);
       }
-      return null;
     }
-
-    /** Used as references for various `Number` constants. */
-    var MAX_SAFE_INTEGER$1 = 9007199254740991;
-
-    /** Used to detect unsigned integer values. */
-    var reIsUint = /^(?:0|[1-9]\d*)$/;
-
-    /**
-     * Checks if `value` is a valid array-like index.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
-     * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
-     */
-    function isIndex(value, length) {
-      length = length == null ? MAX_SAFE_INTEGER$1 : length;
-      return !!length &&
-        (typeof value == 'number' || reIsUint.test(value)) &&
-        (value > -1 && value % 1 == 0 && value < length);
-    }
-
-    /** Used for built-in method references. */
-    var objectProto$5 = Object.prototype;
-
-    /**
-     * Checks if `value` is likely a prototype object.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is a prototype, else `false`.
-     */
-    function isPrototype(value) {
-      var Ctor = value && value.constructor,
-          proto = (typeof Ctor == 'function' && Ctor.prototype) || objectProto$5;
-
-      return value === proto;
-    }
-
-    /**
-     * Creates an array of the own enumerable property names of `object`.
-     *
-     * **Note:** Non-object values are coerced to objects. See the
-     * [ES spec](http://ecma-international.org/ecma-262/6.0/#sec-object.keys)
-     * for more details.
-     *
-     * @static
-     * @since 0.1.0
-     * @memberOf _
-     * @category Object
-     * @param {Object} object The object to query.
-     * @returns {Array} Returns the array of property names.
-     * @example
-     *
-     * function Foo() {
-     *   this.a = 1;
-     *   this.b = 2;
-     * }
-     *
-     * Foo.prototype.c = 3;
-     *
-     * _.keys(new Foo);
-     * // => ['a', 'b'] (iteration order is not guaranteed)
-     *
-     * _.keys('hi');
-     * // => ['0', '1']
-     */
-    function keys(object) {
-      var isProto = isPrototype(object);
-      if (!(isProto || isArrayLike(object))) {
-        return baseKeys(object);
-      }
-      var indexes = indexKeys(object),
-          skipIndexes = !!indexes,
-          result = indexes || [],
-          length = result.length;
-
-      for (var key in object) {
-        if (baseHas(object, key) &&
-            !(skipIndexes && (key == 'length' || isIndex(key, length))) &&
-            !(isProto && key == 'constructor')) {
-          result.push(key);
-        }
+    return result;
+  }
+
+  function iterator(coll) {
+      var i = -1;
+      var len;
+      if (isArrayLike(coll)) {
+          len = coll.length;
+          return function next() {
+              i++;
+              return i < len ? { value: coll[i], key: i } : null;
+          };
       }
-      return result;
-    }
-
-    function iterator(coll) {
-        var i = -1;
-        var len;
-        if (isArrayLike(coll)) {
-            len = coll.length;
-            return function next() {
-                i++;
-                return i < len ? { value: coll[i], key: i } : null;
-            };
-        }
-
-        var iterate = getIterator(coll);
-        if (iterate) {
-            return function next() {
-                var item = iterate.next();
-                if (item.done) return null;
-                i++;
-                return { value: item.value, key: i };
-            };
-        }
-
-        var okeys = keys(coll);
-        len = okeys.length;
-        return function next() {
-            i++;
-            var key = okeys[i];
-            return i < len ? { value: coll[key], key: key } : null;
-        };
-    }
-
-    function onlyOnce(fn) {
-        return function () {
-            if (fn === null) throw new Error("Callback was already called.");
-            var callFn = fn;
-            fn = null;
-            callFn.apply(this, arguments);
-        };
-    }
-
-    function _eachOfLimit(limit) {
-        return function (obj, iteratee, callback) {
-            callback = once(callback || noop);
-            obj = obj || [];
-            var nextElem = iterator(obj);
-            if (limit <= 0) {
-                return callback(null);
-            }
-            var done = false;
-            var running = 0;
-            var errored = false;
-
-            (function replenish() {
-                if (done && running <= 0) {
-                    return callback(null);
-                }
-
-                while (running < limit && !errored) {
-                    var elem = nextElem();
-                    if (elem === null) {
-                        done = true;
-                        if (running <= 0) {
-                            callback(null);
-                        }
-                        return;
-                    }
-                    running += 1;
-                    iteratee(elem.value, elem.key, onlyOnce(function (err) {
-                        running -= 1;
-                        if (err) {
-                            callback(err);
-                            errored = true;
-                        } else {
-                            replenish();
-                        }
-                    }));
-                }
-            })();
-        };
-    }
-
-    function doParallelLimit(fn) {
-        return function (obj, limit, iteratee, callback) {
-            return fn(_eachOfLimit(limit), obj, iteratee, callback);
-        };
-    }
-
-    function _asyncMap(eachfn, arr, iteratee, callback) {
-        callback = once(callback || noop);
-        arr = arr || [];
-        var results = [];
-        var counter = 0;
-
-        eachfn(arr, function (value, _, callback) {
-            var index = counter++;
-            iteratee(value, function (err, v) {
-                results[index] = v;
-                callback(err);
-            });
-        }, function (err) {
-            callback(err, results);
-        });
-    }
-
-    /**
-     * The same as `map` but runs a maximum of `limit` async operations at a time.
-     *
-     * @name mapLimit
-     * @static
-     * @memberOf async
-     * @see async.map
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A function to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, transformed)` which must be called
-     * once it has completed with an error (which can be `null`) and a transformed
-     * item. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called when all `iteratee`
-     * functions have finished, or an error occurs. Results is an array of the
-     * transformed items from the `coll`. Invoked with (err, results).
-     */
-    var mapLimit = doParallelLimit(_asyncMap);
-
-    function doLimit(fn, limit) {
-        return function (iterable, iteratee, callback) {
-            return fn(iterable, limit, iteratee, callback);
-        };
-    }
-
-    /**
-     * Produces a new collection of values by mapping each value in `coll` through
-     * the `iteratee` function. The `iteratee` is called with an item from `coll`
-     * and a callback for when it has finished processing. Each of these callback
-     * takes 2 arguments: an `error`, and the transformed item from `coll`. If
-     * `iteratee` passes an error to its callback, the main `callback` (for the
-     * `map` function) is immediately called with the error.
-     *
-     * Note, that since this function applies the `iteratee` to each item in
-     * parallel, there is no guarantee that the `iteratee` functions will complete
-     * in order. However, the results array will be in the same order as the
-     * original `coll`.
-     *
-     * If `map` is passed an Object, the results will be an Array.  The results
-     * will roughly be in the order of the original Objects' keys (but this can
-     * vary across JavaScript engines)
-     *
-     * @name map
-     * @static
-     * @memberOf async
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, transformed)` which must be called
-     * once it has completed with an error (which can be `null`) and a
-     * transformed item. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called when all `iteratee`
-     * functions have finished, or an error occurs. Results is an Array of the
-     * transformed items from the `coll`. Invoked with (err, results).
-     * @example
-     *
-     * async.map(['file1','file2','file3'], fs.stat, function(err, results) {
-     *     // results is now an array of stats for each file
-     * });
-     */
-    var map = doLimit(mapLimit, Infinity);
-
-    /**
-     * Applies the provided arguments to each function in the array, calling
-     * `callback` after all functions have completed. If you only provide the first
-     * argument, then it will return a function which lets you pass in the
-     * arguments as if it were a single function call.
-     *
-     * @name applyEach
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Array|Object} fns - A collection of asynchronous functions to all
-     * call with the same arguments
-     * @param {...*} [args] - any number of separate arguments to pass to the
-     * function.
-     * @param {Function} [callback] - the final argument should be the callback,
-     * called when all functions have completed processing.
-     * @returns {Function} - If only the first argument is provided, it will return
-     * a function which lets you pass in the arguments as if it were a single
-     * function call.
-     * @example
-     *
-     * async.applyEach([enableSearch, updateSchema], 'bucket', callback);
-     *
-     * // partial application example:
-     * async.each(
-     *     buckets,
-     *     async.applyEach([enableSearch, updateSchema]),
-     *     callback
-     * );
-     */
-    var applyEach = applyEach$1(map);
-
-    /**
-     * The same as `map` but runs only a single async operation at a time.
-     *
-     * @name mapSeries
-     * @static
-     * @memberOf async
-     * @see async.map
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, transformed)` which must be called
-     * once it has completed with an error (which can be `null`) and a
-     * transformed item. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called when all `iteratee`
-     * functions have finished, or an error occurs. Results is an array of the
-     * transformed items from the `coll`. Invoked with (err, results).
-     */
-    var mapSeries = doLimit(mapLimit, 1);
-
-    /**
-     * The same as `applyEach` but runs only a single async operation at a time.
-     *
-     * @name applyEachSeries
-     * @static
-     * @memberOf async
-     * @see async.applyEach
-     * @category Control Flow
-     * @param {Array|Object} fns - A collection of asynchronous functions to all
-     * call with the same arguments
-     * @param {...*} [args] - any number of separate arguments to pass to the
-     * function.
-     * @param {Function} [callback] - the final argument should be the callback,
-     * called when all functions have completed processing.
-     * @returns {Function} - If only the first argument is provided, it will return
-     * a function which lets you pass in the arguments as if it were a single
-     * function call.
-     */
-    var applyEachSeries = applyEach$1(mapSeries);
-
-    /**
-     * Creates a continuation function with some arguments already applied.
-     *
-     * Useful as a shorthand when combined with other control flow functions. Any
-     * arguments passed to the returned function are added to the arguments
-     * originally passed to apply.
-     *
-     * @name apply
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {Function} function - The function you want to eventually apply all
-     * arguments to. Invokes with (arguments...).
-     * @param {...*} arguments... - Any number of arguments to automatically apply
-     * when the continuation is called.
-     * @example
-     *
-     * // using apply
-     * async.parallel([
-     *     async.apply(fs.writeFile, 'testfile1', 'test1'),
-     *     async.apply(fs.writeFile, 'testfile2', 'test2')
-     * ]);
-     *
-     *
-     * // the same process without using apply
-     * async.parallel([
-     *     function(callback) {
-     *         fs.writeFile('testfile1', 'test1', callback);
-     *     },
-     *     function(callback) {
-     *         fs.writeFile('testfile2', 'test2', callback);
-     *     }
-     * ]);
-     *
-     * // It's possible to pass any number of additional arguments when calling the
-     * // continuation:
-     *
-     * node> var fn = async.apply(sys.puts, 'one');
-     * node> fn('two', 'three');
-     * one
-     * two
-     * three
-     */
-    var apply$1 = rest(function (fn, args) {
-        return rest(function (callArgs) {
-            return fn.apply(null, args.concat(callArgs));
-        });
-    });
-
-    /**
-     * Take a sync function and make it async, passing its return value to a
-     * callback. This is useful for plugging sync functions into a waterfall,
-     * series, or other async functions. Any arguments passed to the generated
-     * function will be passed to the wrapped function (except for the final
-     * callback argument). Errors thrown will be passed to the callback.
-     *
-     * If the function passed to `asyncify` returns a Promise, that promises's
-     * resolved/rejected state will be used to call the callback, rather than simply
-     * the synchronous return value.
-     *
-     * This also means you can asyncify ES2016 `async` functions.
-     *
-     * @name asyncify
-     * @static
-     * @memberOf async
-     * @alias wrapSync
-     * @category Util
-     * @param {Function} func - The synchronous function to convert to an
-     * asynchronous function.
-     * @returns {Function} An asynchronous wrapper of the `func`. To be invoked with
-     * (callback).
-     * @example
-     *
-     * // passing a regular synchronous function
-     * async.waterfall([
-     *     async.apply(fs.readFile, filename, "utf8"),
-     *     async.asyncify(JSON.parse),
-     *     function (data, next) {
-     *         // data is the result of parsing the text.
-     *         // If there was a parsing error, it would have been caught.
-     *     }
-     * ], callback);
-     *
-     * // passing a function returning a promise
-     * async.waterfall([
-     *     async.apply(fs.readFile, filename, "utf8"),
-     *     async.asyncify(function (contents) {
-     *         return db.model.create(contents);
-     *     }),
-     *     function (model, next) {
-     *         // `model` is the instantiated model object.
-     *         // If there was an error, this function would be skipped.
-     *     }
-     * ], callback);
-     *
-     * // es6 example
-     * var q = async.queue(async.asyncify(async function(file) {
-     *     var intermediateStep = await processFile(file);
-     *     return await somePromise(intermediateStep)
-     * }));
-     *
-     * q.push(files);
-     */
-    function asyncify(func) {
-        return initialParams(function (args, callback) {
-            var result;
-            try {
-                result = func.apply(this, args);
-            } catch (e) {
-                return callback(e);
-            }
-            // if result is Promise object
-            if (isObject(result) && typeof result.then === 'function') {
-                result.then(function (value) {
-                    callback(null, value);
-                })['catch'](function (err) {
-                    callback(err.message ? err : new Error(err));
-                });
-            } else {
-                callback(null, result);
-            }
-        });
-    }
 
-    /**
-     * A specialized version of `_.forEach` for arrays without support for
-     * iteratee shorthands.
-     *
-     * @private
-     * @param {Array} [array] The array to iterate over.
-     * @param {Function} iteratee The function invoked per iteration.
-     * @returns {Array} Returns `array`.
-     */
-    function arrayEach(array, iteratee) {
-      var index = -1,
-          length = array ? array.length : 0;
-
-      while (++index < length) {
-        if (iteratee(array[index], index, array) === false) {
-          break;
-        }
+      var iterate = getIterator(coll);
+      if (iterate) {
+          return function next() {
+              var item = iterate.next();
+              if (item.done) return null;
+              i++;
+              return { value: item.value, key: i };
+          };
       }
-      return array;
-    }
 
-    /**
-     * Creates a base function for methods like `_.forIn` and `_.forOwn`.
-     *
-     * @private
-     * @param {boolean} [fromRight] Specify iterating from right to left.
-     * @returns {Function} Returns the new base function.
-     */
-    function createBaseFor(fromRight) {
-      return function(object, iteratee, keysFunc) {
-        var index = -1,
-            iterable = Object(object),
-            props = keysFunc(object),
-            length = props.length;
-
-        while (length--) {
-          var key = props[fromRight ? length : ++index];
-          if (iteratee(iterable[key], key, iterable) === false) {
-            break;
+      var okeys = keys(coll);
+      len = okeys.length;
+      return function next() {
+          i++;
+          var key = okeys[i];
+          return i < len ? { value: coll[key], key: key } : null;
+      };
+  }
+
+  function onlyOnce(fn) {
+      return function () {
+          if (fn === null) throw new Error("Callback was already called.");
+          var callFn = fn;
+          fn = null;
+          callFn.apply(this, arguments);
+      };
+  }
+
+  function _eachOfLimit(limit) {
+      return function (obj, iteratee, callback) {
+          callback = once(callback || noop);
+          obj = obj || [];
+          var nextElem = iterator(obj);
+          if (limit <= 0) {
+              return callback(null);
           }
-        }
-        return object;
+          var done = false;
+          var running = 0;
+          var errored = false;
+
+          (function replenish() {
+              if (done && running <= 0) {
+                  return callback(null);
+              }
+
+              while (running < limit && !errored) {
+                  var elem = nextElem();
+                  if (elem === null) {
+                      done = true;
+                      if (running <= 0) {
+                          callback(null);
+                      }
+                      return;
+                  }
+                  running += 1;
+                  /* eslint {no-loop-func: 0} */
+                  iteratee(elem.value, elem.key, onlyOnce(function (err) {
+                      running -= 1;
+                      if (err) {
+                          callback(err);
+                          errored = true;
+                      } else {
+                          replenish();
+                      }
+                  }));
+              }
+          })();
       };
-    }
-
-    /**
-     * The base implementation of `baseForOwn` which iterates over `object`
-     * properties returned by `keysFunc` and invokes `iteratee` for each property.
-     * Iteratee functions may exit iteration early by explicitly returning `false`.
-     *
-     * @private
-     * @param {Object} object The object to iterate over.
-     * @param {Function} iteratee The function invoked per iteration.
-     * @param {Function} keysFunc The function to get the keys of `object`.
-     * @returns {Object} Returns `object`.
-     */
-    var baseFor = createBaseFor();
-
-    /**
-     * The base implementation of `_.forOwn` without support for iteratee shorthands.
-     *
-     * @private
-     * @param {Object} object The object to iterate over.
-     * @param {Function} iteratee The function invoked per iteration.
-     * @returns {Object} Returns `object`.
-     */
-    function baseForOwn(object, iteratee) {
-      return object && baseFor(object, iteratee, keys);
-    }
-
-    /**
-     * Removes all key-value entries from the list cache.
-     *
-     * @private
-     * @name clear
-     * @memberOf ListCache
-     */
-    function listCacheClear() {
-      this.__data__ = [];
-    }
+  }
 
-    /**
-     * Performs a
-     * [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
-     * comparison between two values to determine if they are equivalent.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to compare.
-     * @param {*} other The other value to compare.
-     * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
-     * @example
-     *
-     * var object = { 'user': 'fred' };
-     * var other = { 'user': 'fred' };
-     *
-     * _.eq(object, object);
-     * // => true
-     *
-     * _.eq(object, other);
-     * // => false
-     *
-     * _.eq('a', 'a');
-     * // => true
-     *
-     * _.eq('a', Object('a'));
-     * // => false
-     *
-     * _.eq(NaN, NaN);
-     * // => true
-     */
-    function eq(value, other) {
-      return value === other || (value !== value && other !== other);
+  function doParallelLimit(fn) {
+      return function (obj, limit, iteratee, callback) {
+          return fn(_eachOfLimit(limit), obj, iteratee, callback);
+      };
+  }
+
+  function _asyncMap(eachfn, arr, iteratee, callback) {
+      callback = once(callback || noop);
+      arr = arr || [];
+      var results = [];
+      var counter = 0;
+
+      eachfn(arr, function (value, _, callback) {
+          var index = counter++;
+          iteratee(value, function (err, v) {
+              results[index] = v;
+              callback(err);
+          });
+      }, function (err) {
+          callback(err, results);
+      });
+  }
+
+  /**
+   * The same as [`map`]{@link module:Collections.map} but runs a maximum of `limit` async operations at a time.
+   *
+   * @name mapLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.map]{@link module:Collections.map}
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A function to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, transformed)` which must be called
+   * once it has completed with an error (which can be `null`) and a transformed
+   * item. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called when all `iteratee`
+   * functions have finished, or an error occurs. Results is an array of the
+   * transformed items from the `coll`. Invoked with (err, results).
+   */
+  var mapLimit = doParallelLimit(_asyncMap);
+
+  function doLimit(fn, limit) {
+      return function (iterable, iteratee, callback) {
+          return fn(iterable, limit, iteratee, callback);
+      };
+  }
+
+  /**
+   * Produces a new collection of values by mapping each value in `coll` through
+   * the `iteratee` function. The `iteratee` is called with an item from `coll`
+   * and a callback for when it has finished processing. Each of these callback
+   * takes 2 arguments: an `error`, and the transformed item from `coll`. If
+   * `iteratee` passes an error to its callback, the main `callback` (for the
+   * `map` function) is immediately called with the error.
+   *
+   * Note, that since this function applies the `iteratee` to each item in
+   * parallel, there is no guarantee that the `iteratee` functions will complete
+   * in order. However, the results array will be in the same order as the
+   * original `coll`.
+   *
+   * If `map` is passed an Object, the results will be an Array.  The results
+   * will roughly be in the order of the original Objects' keys (but this can
+   * vary across JavaScript engines)
+   *
+   * @name map
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, transformed)` which must be called
+   * once it has completed with an error (which can be `null`) and a
+   * transformed item. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called when all `iteratee`
+   * functions have finished, or an error occurs. Results is an Array of the
+   * transformed items from the `coll`. Invoked with (err, results).
+   * @example
+   *
+   * async.map(['file1','file2','file3'], fs.stat, function(err, results) {
+   *     // results is now an array of stats for each file
+   * });
+   */
+  var map = doLimit(mapLimit, Infinity);
+
+  /**
+   * Applies the provided arguments to each function in the array, calling
+   * `callback` after all functions have completed. If you only provide the first
+   * argument, then it will return a function which lets you pass in the
+   * arguments as if it were a single function call.
+   *
+   * @name applyEach
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Array|Object} fns - A collection of asynchronous functions to all
+   * call with the same arguments
+   * @param {...*} [args] - any number of separate arguments to pass to the
+   * function.
+   * @param {Function} [callback] - the final argument should be the callback,
+   * called when all functions have completed processing.
+   * @returns {Function} - If only the first argument is provided, it will return
+   * a function which lets you pass in the arguments as if it were a single
+   * function call.
+   * @example
+   *
+   * async.applyEach([enableSearch, updateSchema], 'bucket', callback);
+   *
+   * // partial application example:
+   * async.each(
+   *     buckets,
+   *     async.applyEach([enableSearch, updateSchema]),
+   *     callback
+   * );
+   */
+  var applyEach = applyEach$1(map);
+
+  /**
+   * The same as [`map`]{@link module:Collections.map} but runs only a single async operation at a time.
+   *
+   * @name mapSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.map]{@link module:Collections.map}
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, transformed)` which must be called
+   * once it has completed with an error (which can be `null`) and a
+   * transformed item. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called when all `iteratee`
+   * functions have finished, or an error occurs. Results is an array of the
+   * transformed items from the `coll`. Invoked with (err, results).
+   */
+  var mapSeries = doLimit(mapLimit, 1);
+
+  /**
+   * The same as [`applyEach`]{@link module:ControlFlow.applyEach} but runs only a single async operation at a time.
+   *
+   * @name applyEachSeries
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.applyEach]{@link module:ControlFlow.applyEach}
+   * @category Control Flow
+   * @param {Array|Object} fns - A collection of asynchronous functions to all
+   * call with the same arguments
+   * @param {...*} [args] - any number of separate arguments to pass to the
+   * function.
+   * @param {Function} [callback] - the final argument should be the callback,
+   * called when all functions have completed processing.
+   * @returns {Function} - If only the first argument is provided, it will return
+   * a function which lets you pass in the arguments as if it were a single
+   * function call.
+   */
+  var applyEachSeries = applyEach$1(mapSeries);
+
+  /**
+   * Creates a continuation function with some arguments already applied.
+   *
+   * Useful as a shorthand when combined with other control flow functions. Any
+   * arguments passed to the returned function are added to the arguments
+   * originally passed to apply.
+   *
+   * @name apply
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {Function} function - The function you want to eventually apply all
+   * arguments to. Invokes with (arguments...).
+   * @param {...*} arguments... - Any number of arguments to automatically apply
+   * when the continuation is called.
+   * @example
+   *
+   * // using apply
+   * async.parallel([
+   *     async.apply(fs.writeFile, 'testfile1', 'test1'),
+   *     async.apply(fs.writeFile, 'testfile2', 'test2')
+   * ]);
+   *
+   *
+   * // the same process without using apply
+   * async.parallel([
+   *     function(callback) {
+   *         fs.writeFile('testfile1', 'test1', callback);
+   *     },
+   *     function(callback) {
+   *         fs.writeFile('testfile2', 'test2', callback);
+   *     }
+   * ]);
+   *
+   * // It's possible to pass any number of additional arguments when calling the
+   * // continuation:
+   *
+   * node> var fn = async.apply(sys.puts, 'one');
+   * node> fn('two', 'three');
+   * one
+   * two
+   * three
+   */
+  var apply$1 = rest(function (fn, args) {
+      return rest(function (callArgs) {
+          return fn.apply(null, args.concat(callArgs));
+      });
+  });
+
+  /**
+   * Take a sync function and make it async, passing its return value to a
+   * callback. This is useful for plugging sync functions into a waterfall,
+   * series, or other async functions. Any arguments passed to the generated
+   * function will be passed to the wrapped function (except for the final
+   * callback argument). Errors thrown will be passed to the callback.
+   *
+   * If the function passed to `asyncify` returns a Promise, that promises's
+   * resolved/rejected state will be used to call the callback, rather than simply
+   * the synchronous return value.
+   *
+   * This also means you can asyncify ES2016 `async` functions.
+   *
+   * @name asyncify
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @alias wrapSync
+   * @category Util
+   * @param {Function} func - The synchronous function to convert to an
+   * asynchronous function.
+   * @returns {Function} An asynchronous wrapper of the `func`. To be invoked with
+   * (callback).
+   * @example
+   *
+   * // passing a regular synchronous function
+   * async.waterfall([
+   *     async.apply(fs.readFile, filename, "utf8"),
+   *     async.asyncify(JSON.parse),
+   *     function (data, next) {
+   *         // data is the result of parsing the text.
+   *         // If there was a parsing error, it would have been caught.
+   *     }
+   * ], callback);
+   *
+   * // passing a function returning a promise
+   * async.waterfall([
+   *     async.apply(fs.readFile, filename, "utf8"),
+   *     async.asyncify(function (contents) {
+   *         return db.model.create(contents);
+   *     }),
+   *     function (model, next) {
+   *         // `model` is the instantiated model object.
+   *         // If there was an error, this function would be skipped.
+   *     }
+   * ], callback);
+   *
+   * // es6 example
+   * var q = async.queue(async.asyncify(async function(file) {
+   *     var intermediateStep = await processFile(file);
+   *     return await somePromise(intermediateStep)
+   * }));
+   *
+   * q.push(files);
+   */
+  function asyncify(func) {
+      return initialParams(function (args, callback) {
+          var result;
+          try {
+              result = func.apply(this, args);
+          } catch (e) {
+              return callback(e);
+          }
+          // if result is Promise object
+          if (isObject(result) && typeof result.then === 'function') {
+              result.then(function (value) {
+                  callback(null, value);
+              }, function (err) {
+                  callback(err.message ? err : new Error(err));
+              });
+          } else {
+              callback(null, result);
+          }
+      });
+  }
+
+  /**
+   * A specialized version of `_.forEach` for arrays without support for
+   * iteratee shorthands.
+   *
+   * @private
+   * @param {Array} [array] The array to iterate over.
+   * @param {Function} iteratee The function invoked per iteration.
+   * @returns {Array} Returns `array`.
+   */
+  function arrayEach(array, iteratee) {
+    var index = -1,
+        length = array ? array.length : 0;
+
+    while (++index < length) {
+      if (iteratee(array[index], index, array) === false) {
+        break;
+      }
     }
+    return array;
+  }
+
+  /**
+   * Creates a base function for methods like `_.forIn` and `_.forOwn`.
+   *
+   * @private
+   * @param {boolean} [fromRight] Specify iterating from right to left.
+   * @returns {Function} Returns the new base function.
+   */
+  function createBaseFor(fromRight) {
+    return function(object, iteratee, keysFunc) {
+      var index = -1,
+          iterable = Object(object),
+          props = keysFunc(object),
+          length = props.length;
 
-    /**
-     * Gets the index at which the `key` is found in `array` of key-value pairs.
-     *
-     * @private
-     * @param {Array} array The array to search.
-     * @param {*} key The key to search for.
-     * @returns {number} Returns the index of the matched value, else `-1`.
-     */
-    function assocIndexOf(array, key) {
-      var length = array.length;
       while (length--) {
-        if (eq(array[length][0], key)) {
-          return length;
+        var key = props[fromRight ? length : ++index];
+        if (iteratee(iterable[key], key, iterable) === false) {
+          break;
         }
       }
-      return -1;
-    }
-
-    /** Used for built-in method references. */
-    var arrayProto = Array.prototype;
-
-    /** Built-in value references. */
-    var splice = arrayProto.splice;
-
-    /**
-     * Removes `key` and its value from the list cache.
-     *
-     * @private
-     * @name delete
-     * @memberOf ListCache
-     * @param {string} key The key of the value to remove.
-     * @returns {boolean} Returns `true` if the entry was removed, else `false`.
-     */
-    function listCacheDelete(key) {
-      var data = this.__data__,
-          index = assocIndexOf(data, key);
-
-      if (index < 0) {
-        return false;
-      }
-      var lastIndex = data.length - 1;
-      if (index == lastIndex) {
-        data.pop();
-      } else {
-        splice.call(data, index, 1);
+      return object;
+    };
+  }
+
+  /**
+   * The base implementation of `baseForOwn` which iterates over `object`
+   * properties returned by `keysFunc` and invokes `iteratee` for each property.
+   * Iteratee functions may exit iteration early by explicitly returning `false`.
+   *
+   * @private
+   * @param {Object} object The object to iterate over.
+   * @param {Function} iteratee The function invoked per iteration.
+   * @param {Function} keysFunc The function to get the keys of `object`.
+   * @returns {Object} Returns `object`.
+   */
+  var baseFor = createBaseFor();
+
+  /**
+   * The base implementation of `_.forOwn` without support for iteratee shorthands.
+   *
+   * @private
+   * @param {Object} object The object to iterate over.
+   * @param {Function} iteratee The function invoked per iteration.
+   * @returns {Object} Returns `object`.
+   */
+  function baseForOwn(object, iteratee) {
+    return object && baseFor(object, iteratee, keys);
+  }
+
+  /**
+   * Gets the index at which the first occurrence of `NaN` is found in `array`.
+   *
+   * @private
+   * @param {Array} array The array to search.
+   * @param {number} fromIndex The index to search from.
+   * @param {boolean} [fromRight] Specify iterating from right to left.
+   * @returns {number} Returns the index of the matched `NaN`, else `-1`.
+   */
+  function indexOfNaN(array, fromIndex, fromRight) {
+    var length = array.length,
+        index = fromIndex + (fromRight ? 1 : -1);
+
+    while ((fromRight ? index-- : ++index < length)) {
+      var other = array[index];
+      if (other !== other) {
+        return index;
       }
-      return true;
-    }
-
-    /**
-     * Gets the list cache value for `key`.
-     *
-     * @private
-     * @name get
-     * @memberOf ListCache
-     * @param {string} key The key of the value to get.
-     * @returns {*} Returns the entry value.
-     */
-    function listCacheGet(key) {
-      var data = this.__data__,
-          index = assocIndexOf(data, key);
-
-      return index < 0 ? undefined : data[index][1];
-    }
-
-    /**
-     * Checks if a list cache value for `key` exists.
-     *
-     * @private
-     * @name has
-     * @memberOf ListCache
-     * @param {string} key The key of the entry to check.
-     * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
-     */
-    function listCacheHas(key) {
-      return assocIndexOf(this.__data__, key) > -1;
     }
-
-    /**
-     * Sets the list cache `key` to `value`.
-     *
-     * @private
-     * @name set
-     * @memberOf ListCache
-     * @param {string} key The key of the value to set.
-     * @param {*} value The value to set.
-     * @returns {Object} Returns the list cache instance.
-     */
-    function listCacheSet(key, value) {
-      var data = this.__data__,
-          index = assocIndexOf(data, key);
-
-      if (index < 0) {
-        data.push([key, value]);
-      } else {
-        data[index][1] = value;
+    return -1;
+  }
+
+  /**
+   * The base implementation of `_.indexOf` without `fromIndex` bounds checks.
+   *
+   * @private
+   * @param {Array} array The array to search.
+   * @param {*} value The value to search for.
+   * @param {number} fromIndex The index to search from.
+   * @returns {number} Returns the index of the matched value, else `-1`.
+   */
+  function baseIndexOf(array, value, fromIndex) {
+    if (value !== value) {
+      return indexOfNaN(array, fromIndex);
+    }
+    var index = fromIndex - 1,
+        length = array.length;
+
+    while (++index < length) {
+      if (array[index] === value) {
+        return index;
       }
-      return this;
     }
-
-    /**
-     * Creates an list cache object.
-     *
-     * @private
-     * @constructor
-     * @param {Array} [entries] The key-value pairs to cache.
-     */
-    function ListCache(entries) {
-      var index = -1,
-          length = entries ? entries.length : 0;
-
-      this.clear();
-      while (++index < length) {
-        var entry = entries[index];
-        this.set(entry[0], entry[1]);
+    return -1;
+  }
+
+  /**
+   * Determines the best order for running the functions in `tasks`, based on
+   * their requirements. Each function can optionally depend on other functions
+   * being completed first, and each function is run as soon as its requirements
+   * are satisfied.
+   *
+   * If any of the functions pass an error to their callback, the `auto` sequence
+   * will stop. Further tasks will not execute (so any other functions depending
+   * on it will not run), and the main `callback` is immediately called with the
+   * error.
+   *
+   * Functions also receive an object containing the results of functions which
+   * have completed so far as the first argument, if they have dependencies. If a
+   * task function has no dependencies, it will only be passed a callback.
+   *
+   * @name auto
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Object} tasks - An object. Each of its properties is either a
+   * function or an array of requirements, with the function itself the last item
+   * in the array. The object's key of a property serves as the name of the task
+   * defined by that property, i.e. can be used when specifying requirements for
+   * other tasks. The function receives one or two arguments:
+   * * a `results` object, containing the results of the previously executed
+   *   functions, only passed if the task has any dependencies,
+   * * a `callback(err, result)` function, which must be called when finished,
+   *   passing an `error` (which can be `null`) and the result of the function's
+   *   execution.
+   * @param {number} [concurrency=Infinity] - An optional `integer` for
+   * determining the maximum number of tasks that can be run in parallel. By
+   * default, as many as possible.
+   * @param {Function} [callback] - An optional callback which is called when all
+   * the tasks have been completed. It receives the `err` argument if any `tasks`
+   * pass an error to their callback. Results are always returned; however, if an
+   * error occurs, no further `tasks` will be performed, and the results object
+   * will only contain partial results. Invoked with (err, results).
+   * @returns undefined
+   * @example
+   *
+   * async.auto({
+   *     // this function will just be passed a callback
+   *     readData: async.apply(fs.readFile, 'data.txt', 'utf-8'),
+   *     showData: ['readData', function(results, cb) {
+   *         // results.readData is the file's contents
+   *         // ...
+   *     }]
+   * }, callback);
+   *
+   * async.auto({
+   *     get_data: function(callback) {
+   *         console.log('in get_data');
+   *         // async code to get some data
+   *         callback(null, 'data', 'converted to array');
+   *     },
+   *     make_folder: function(callback) {
+   *         console.log('in make_folder');
+   *         // async code to create a directory to store a file in
+   *         // this is run at the same time as getting the data
+   *         callback(null, 'folder');
+   *     },
+   *     write_file: ['get_data', 'make_folder', function(results, callback) {
+   *         console.log('in write_file', JSON.stringify(results));
+   *         // once there is some data and the directory exists,
+   *         // write the data to a file in the directory
+   *         callback(null, 'filename');
+   *     }],
+   *     email_link: ['write_file', function(results, callback) {
+   *         console.log('in email_link', JSON.stringify(results));
+   *         // once the file is written let's email a link to it...
+   *         // results.write_file contains the filename returned by write_file.
+   *         callback(null, {'file':results.write_file, 'email':'user@example.com'});
+   *     }]
+   * }, function(err, results) {
+   *     console.log('err = ', err);
+   *     console.log('results = ', results);
+   * });
+   */
+  function auto (tasks, concurrency, callback) {
+      if (typeof concurrency === 'function') {
+          // concurrency is optional, shift the args.
+          callback = concurrency;
+          concurrency = null;
       }
-    }
-
-    // Add methods to `ListCache`.
-    ListCache.prototype.clear = listCacheClear;
-    ListCache.prototype['delete'] = listCacheDelete;
-    ListCache.prototype.get = listCacheGet;
-    ListCache.prototype.has = listCacheHas;
-    ListCache.prototype.set = listCacheSet;
-
-    /**
-     * Removes all key-value entries from the stack.
-     *
-     * @private
-     * @name clear
-     * @memberOf Stack
-     */
-    function stackClear() {
-      this.__data__ = new ListCache;
-    }
-
-    /**
-     * Removes `key` and its value from the stack.
-     *
-     * @private
-     * @name delete
-     * @memberOf Stack
-     * @param {string} key The key of the value to remove.
-     * @returns {boolean} Returns `true` if the entry was removed, else `false`.
-     */
-    function stackDelete(key) {
-      return this.__data__['delete'](key);
-    }
-
-    /**
-     * Gets the stack value for `key`.
-     *
-     * @private
-     * @name get
-     * @memberOf Stack
-     * @param {string} key The key of the value to get.
-     * @returns {*} Returns the entry value.
-     */
-    function stackGet(key) {
-      return this.__data__.get(key);
-    }
-
-    /**
-     * Checks if a stack value for `key` exists.
-     *
-     * @private
-     * @name has
-     * @memberOf Stack
-     * @param {string} key The key of the entry to check.
-     * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
-     */
-    function stackHas(key) {
-      return this.__data__.has(key);
-    }
-
-    /**
-     * Checks if `value` is a host object in IE < 9.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is a host object, else `false`.
-     */
-    function isHostObject(value) {
-      // Many host objects are `Object` objects that can coerce to strings
-      // despite having improperly defined `toString` methods.
-      var result = false;
-      if (value != null && typeof value.toString != 'function') {
-        try {
-          result = !!(value + '');
-        } catch (e) {}
+      callback = once(callback || noop);
+      var keys$$ = keys(tasks);
+      var numTasks = keys$$.length;
+      if (!numTasks) {
+          return callback(null);
+      }
+      if (!concurrency) {
+          concurrency = numTasks;
       }
-      return result;
-    }
-
-    /**
-     * Checks if `value` is a global object.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @returns {null|Object} Returns `value` if it's a global object, else `null`.
-     */
-    function checkGlobal(value) {
-      return (value && value.Object === Object) ? value : null;
-    }
 
-    /** Detect free variable `global` from Node.js. */
-    var freeGlobal = checkGlobal(typeof global == 'object' && global);
+      var results = {};
+      var runningTasks = 0;
+      var hasError = false;
 
-    /** Detect free variable `self`. */
-    var freeSelf = checkGlobal(typeof self == 'object' && self);
+      var listeners = {};
 
-    /** Detect `this` as the global object. */
-    var thisGlobal = checkGlobal(typeof this == 'object' && this);
+      var readyTasks = [];
 
-    /** Used as a reference to the global object. */
-    var root = freeGlobal || freeSelf || thisGlobal || Function('return this')();
+      // for cycle detection:
+      var readyToCheck = []; // tasks that have been identified as reachable
+      // without the possibility of returning to an ancestor task
+      var uncheckedDependencies = {};
 
-    /** Used to detect overreaching core-js shims. */
-    var coreJsData = root['__core-js_shared__'];
+      baseForOwn(tasks, function (task, key) {
+          if (!isArray(task)) {
+              // no dependencies
+              enqueueTask(key, [task]);
+              readyToCheck.push(key);
+              return;
+          }
 
-    /** Used to detect methods masquerading as native. */
-    var maskSrcKey = (function() {
-      var uid = /[^.]+$/.exec(coreJsData && coreJsData.keys && coreJsData.keys.IE_PROTO || '');
-      return uid ? ('Symbol(src)_1.' + uid) : '';
-    }());
+          var dependencies = task.slice(0, task.length - 1);
+          var remainingDependencies = dependencies.length;
+          if (remainingDependencies === 0) {
+              enqueueTask(key, task);
+              readyToCheck.push(key);
+              return;
+          }
+          uncheckedDependencies[key] = remainingDependencies;
+
+          arrayEach(dependencies, function (dependencyName) {
+              if (!tasks[dependencyName]) {
+                  throw new Error('async.auto task `' + key + '` has a non-existent dependency in ' + dependencies.join(', '));
+              }
+              addListener(dependencyName, function () {
+                  remainingDependencies--;
+                  if (remainingDependencies === 0) {
+                      enqueueTask(key, task);
+                  }
+              });
+          });
+      });
 
-    /**
-     * Checks if `func` has its source masked.
-     *
-     * @private
-     * @param {Function} func The function to check.
-     * @returns {boolean} Returns `true` if `func` is masked, else `false`.
-     */
-    function isMasked(func) {
-      return !!maskSrcKey && (maskSrcKey in func);
-    }
+      checkForDeadlocks();
+      processQueue();
 
-    /** Used to resolve the decompiled source of functions. */
-    var funcToString$1 = Function.prototype.toString;
-
-    /**
-     * Converts `func` to its source code.
-     *
-     * @private
-     * @param {Function} func The function to process.
-     * @returns {string} Returns the source code.
-     */
-    function toSource(func) {
-      if (func != null) {
-        try {
-          return funcToString$1.call(func);
-        } catch (e) {}
-        try {
-          return (func + '');
-        } catch (e) {}
+      function enqueueTask(key, task) {
+          readyTasks.push(function () {
+              runTask(key, task);
+          });
       }
-      return '';
-    }
 
-    /**
-     * Used to match `RegExp`
-     * [syntax characters](http://ecma-international.org/ecma-262/6.0/#sec-patterns).
-     */
-    var reRegExpChar = /[\\^$.*+?()[\]{}|]/g;
-
-    /** Used to detect host constructors (Safari). */
-    var reIsHostCtor = /^\[object .+?Constructor\]$/;
-
-    /** Used for built-in method references. */
-    var objectProto$6 = Object.prototype;
-
-    /** Used to resolve the decompiled source of functions. */
-    var funcToString = Function.prototype.toString;
-
-    /** Used to check objects for own properties. */
-    var hasOwnProperty$2 = objectProto$6.hasOwnProperty;
-
-    /** Used to detect if a method is native. */
-    var reIsNative = RegExp('^' +
-      funcToString.call(hasOwnProperty$2).replace(reRegExpChar, '\\$&')
-      .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?') + '$'
-    );
-
-    /**
-     * The base implementation of `_.isNative` without bad shim checks.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is a native function,
-     *  else `false`.
-     */
-    function baseIsNative(value) {
-      if (!isObject(value) || isMasked(value)) {
-        return false;
+      function processQueue() {
+          if (readyTasks.length === 0 && runningTasks === 0) {
+              return callback(null, results);
+          }
+          while (readyTasks.length && runningTasks < concurrency) {
+              var run = readyTasks.shift();
+              run();
+          }
       }
-      var pattern = (isFunction(value) || isHostObject(value)) ? reIsNative : reIsHostCtor;
-      return pattern.test(toSource(value));
-    }
 
-    /**
-     * Gets the value at `key` of `object`.
-     *
-     * @private
-     * @param {Object} [object] The object to query.
-     * @param {string} key The key of the property to get.
-     * @returns {*} Returns the property value.
-     */
-    function getValue(object, key) {
-      return object == null ? undefined : object[key];
-    }
-
-    /**
-     * Gets the native function at `key` of `object`.
-     *
-     * @private
-     * @param {Object} object The object to query.
-     * @param {string} key The key of the method to get.
-     * @returns {*} Returns the function if it's native, else `undefined`.
-     */
-    function getNative(object, key) {
-      var value = getValue(object, key);
-      return baseIsNative(value) ? value : undefined;
-    }
-
-    /* Built-in method references that are verified to be native. */
-    var nativeCreate = getNative(Object, 'create');
-
-    /**
-     * Removes all key-value entries from the hash.
-     *
-     * @private
-     * @name clear
-     * @memberOf Hash
-     */
-    function hashClear() {
-      this.__data__ = nativeCreate ? nativeCreate(null) : {};
-    }
-
-    /**
-     * Removes `key` and its value from the hash.
-     *
-     * @private
-     * @name delete
-     * @memberOf Hash
-     * @param {Object} hash The hash to modify.
-     * @param {string} key The key of the value to remove.
-     * @returns {boolean} Returns `true` if the entry was removed, else `false`.
-     */
-    function hashDelete(key) {
-      return this.has(key) && delete this.__data__[key];
-    }
+      function addListener(taskName, fn) {
+          var taskListeners = listeners[taskName];
+          if (!taskListeners) {
+              taskListeners = listeners[taskName] = [];
+          }
 
-    /** Used to stand-in for `undefined` hash values. */
-    var HASH_UNDEFINED = '__lodash_hash_undefined__';
-
-    /** Used for built-in method references. */
-    var objectProto$7 = Object.prototype;
-
-    /** Used to check objects for own properties. */
-    var hasOwnProperty$3 = objectProto$7.hasOwnProperty;
-
-    /**
-     * Gets the hash value for `key`.
-     *
-     * @private
-     * @name get
-     * @memberOf Hash
-     * @param {string} key The key of the value to get.
-     * @returns {*} Returns the entry value.
-     */
-    function hashGet(key) {
-      var data = this.__data__;
-      if (nativeCreate) {
-        var result = data[key];
-        return result === HASH_UNDEFINED ? undefined : result;
+          taskListeners.push(fn);
       }
-      return hasOwnProperty$3.call(data, key) ? data[key] : undefined;
-    }
-
-    /** Used for built-in method references. */
-    var objectProto$8 = Object.prototype;
-
-    /** Used to check objects for own properties. */
-    var hasOwnProperty$4 = objectProto$8.hasOwnProperty;
-
-    /**
-     * Checks if a hash value for `key` exists.
-     *
-     * @private
-     * @name has
-     * @memberOf Hash
-     * @param {string} key The key of the entry to check.
-     * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
-     */
-    function hashHas(key) {
-      var data = this.__data__;
-      return nativeCreate ? data[key] !== undefined : hasOwnProperty$4.call(data, key);
-    }
 
-    /** Used to stand-in for `undefined` hash values. */
-    var HASH_UNDEFINED$1 = '__lodash_hash_undefined__';
-
-    /**
-     * Sets the hash `key` to `value`.
-     *
-     * @private
-     * @name set
-     * @memberOf Hash
-     * @param {string} key The key of the value to set.
-     * @param {*} value The value to set.
-     * @returns {Object} Returns the hash instance.
-     */
-    function hashSet(key, value) {
-      var data = this.__data__;
-      data[key] = (nativeCreate && value === undefined) ? HASH_UNDEFINED$1 : value;
-      return this;
-    }
-
-    /**
-     * Creates a hash object.
-     *
-     * @private
-     * @constructor
-     * @param {Array} [entries] The key-value pairs to cache.
-     */
-    function Hash(entries) {
-      var index = -1,
-          length = entries ? entries.length : 0;
-
-      this.clear();
-      while (++index < length) {
-        var entry = entries[index];
-        this.set(entry[0], entry[1]);
+      function taskComplete(taskName) {
+          var taskListeners = listeners[taskName] || [];
+          arrayEach(taskListeners, function (fn) {
+              fn();
+          });
+          processQueue();
       }
-    }
-
-    // Add methods to `Hash`.
-    Hash.prototype.clear = hashClear;
-    Hash.prototype['delete'] = hashDelete;
-    Hash.prototype.get = hashGet;
-    Hash.prototype.has = hashHas;
-    Hash.prototype.set = hashSet;
-
-    /* Built-in method references that are verified to be native. */
-    var Map = getNative(root, 'Map');
-
-    /**
-     * Removes all key-value entries from the map.
-     *
-     * @private
-     * @name clear
-     * @memberOf MapCache
-     */
-    function mapCacheClear() {
-      this.__data__ = {
-        'hash': new Hash,
-        'map': new (Map || ListCache),
-        'string': new Hash
-      };
-    }
-
-    /**
-     * Checks if `value` is suitable for use as unique object key.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is suitable, else `false`.
-     */
-    function isKeyable(value) {
-      var type = typeof value;
-      return (type == 'string' || type == 'number' || type == 'symbol' || type == 'boolean')
-        ? (value !== '__proto__')
-        : (value === null);
-    }
-
-    /**
-     * Gets the data for `map`.
-     *
-     * @private
-     * @param {Object} map The map to query.
-     * @param {string} key The reference key.
-     * @returns {*} Returns the map data.
-     */
-    function getMapData(map, key) {
-      var data = map.__data__;
-      return isKeyable(key)
-        ? data[typeof key == 'string' ? 'string' : 'hash']
-        : data.map;
-    }
-
-    /**
-     * Removes `key` and its value from the map.
-     *
-     * @private
-     * @name delete
-     * @memberOf MapCache
-     * @param {string} key The key of the value to remove.
-     * @returns {boolean} Returns `true` if the entry was removed, else `false`.
-     */
-    function mapCacheDelete(key) {
-      return getMapData(this, key)['delete'](key);
-    }
-
-    /**
-     * Gets the map value for `key`.
-     *
-     * @private
-     * @name get
-     * @memberOf MapCache
-     * @param {string} key The key of the value to get.
-     * @returns {*} Returns the entry value.
-     */
-    function mapCacheGet(key) {
-      return getMapData(this, key).get(key);
-    }
-
-    /**
-     * Checks if a map value for `key` exists.
-     *
-     * @private
-     * @name has
-     * @memberOf MapCache
-     * @param {string} key The key of the entry to check.
-     * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
-     */
-    function mapCacheHas(key) {
-      return getMapData(this, key).has(key);
-    }
 
-    /**
-     * Sets the map `key` to `value`.
-     *
-     * @private
-     * @name set
-     * @memberOf MapCache
-     * @param {string} key The key of the value to set.
-     * @param {*} value The value to set.
-     * @returns {Object} Returns the map cache instance.
-     */
-    function mapCacheSet(key, value) {
-      getMapData(this, key).set(key, value);
-      return this;
-    }
+      function runTask(key, task) {
+          if (hasError) return;
+
+          var taskCallback = onlyOnce(rest(function (err, args) {
+              runningTasks--;
+              if (args.length <= 1) {
+                  args = args[0];
+              }
+              if (err) {
+                  var safeResults = {};
+                  baseForOwn(results, function (val, rkey) {
+                      safeResults[rkey] = val;
+                  });
+                  safeResults[key] = args;
+                  hasError = true;
+                  listeners = [];
+
+                  callback(err, safeResults);
+              } else {
+                  results[key] = args;
+                  taskComplete(key);
+              }
+          }));
+
+          runningTasks++;
+          var taskFn = task[task.length - 1];
+          if (task.length > 1) {
+              taskFn(results, taskCallback);
+          } else {
+              taskFn(taskCallback);
+          }
+      }
 
-    /**
-     * Creates a map cache object to store key-value pairs.
-     *
-     * @private
-     * @constructor
-     * @param {Array} [entries] The key-value pairs to cache.
-     */
-    function MapCache(entries) {
-      var index = -1,
-          length = entries ? entries.length : 0;
+      function checkForDeadlocks() {
+          // Kahn's algorithm
+          // https://en.wikipedia.org/wiki/Topological_sorting#Kahn.27s_algorithm
+          // http://connalle.blogspot.com/2013/10/topological-sortingkahn-algorithm.html
+          var currentTask;
+          var counter = 0;
+          while (readyToCheck.length) {
+              currentTask = readyToCheck.pop();
+              counter++;
+              arrayEach(getDependents(currentTask), function (dependent) {
+                  if (! --uncheckedDependencies[dependent]) {
+                      readyToCheck.push(dependent);
+                  }
+              });
+          }
 
-      this.clear();
-      while (++index < length) {
-        var entry = entries[index];
-        this.set(entry[0], entry[1]);
+          if (counter !== numTasks) {
+              throw new Error('async.auto cannot execute tasks due to a recursive dependency');
+          }
       }
-    }
 
-    // Add methods to `MapCache`.
-    MapCache.prototype.clear = mapCacheClear;
-    MapCache.prototype['delete'] = mapCacheDelete;
-    MapCache.prototype.get = mapCacheGet;
-    MapCache.prototype.has = mapCacheHas;
-    MapCache.prototype.set = mapCacheSet;
-
-    /** Used as the size to enable large array optimizations. */
-    var LARGE_ARRAY_SIZE = 200;
-
-    /**
-     * Sets the stack `key` to `value`.
-     *
-     * @private
-     * @name set
-     * @memberOf Stack
-     * @param {string} key The key of the value to set.
-     * @param {*} value The value to set.
-     * @returns {Object} Returns the stack cache instance.
-     */
-    function stackSet(key, value) {
-      var cache = this.__data__;
-      if (cache instanceof ListCache && cache.__data__.length == LARGE_ARRAY_SIZE) {
-        cache = this.__data__ = new MapCache(cache.__data__);
+      function getDependents(taskName) {
+          var result = [];
+          baseForOwn(tasks, function (task, key) {
+              if (isArray(task) && baseIndexOf(task, taskName, 0) >= 0) {
+                  result.push(key);
+              }
+          });
+          return result;
       }
-      cache.set(key, value);
-      return this;
+  }
+
+  /**
+   * A specialized version of `_.map` for arrays without support for iteratee
+   * shorthands.
+   *
+   * @private
+   * @param {Array} [array] The array to iterate over.
+   * @param {Function} iteratee The function invoked per iteration.
+   * @returns {Array} Returns the new mapped array.
+   */
+  function arrayMap(array, iteratee) {
+    var index = -1,
+        length = array ? array.length : 0,
+        result = Array(length);
+
+    while (++index < length) {
+      result[index] = iteratee(array[index], index, array);
+    }
+    return result;
+  }
+
+  /**
+   * Copies the values of `source` to `array`.
+   *
+   * @private
+   * @param {Array} source The array to copy values from.
+   * @param {Array} [array=[]] The array to copy values to.
+   * @returns {Array} Returns `array`.
+   */
+  function copyArray(source, array) {
+    var index = -1,
+        length = source.length;
+
+    array || (array = Array(length));
+    while (++index < length) {
+      array[index] = source[index];
+    }
+    return array;
+  }
+
+  /**
+   * Checks if `value` is a global object.
+   *
+   * @private
+   * @param {*} value The value to check.
+   * @returns {null|Object} Returns `value` if it's a global object, else `null`.
+   */
+  function checkGlobal(value) {
+    return (value && value.Object === Object) ? value : null;
+  }
+
+  /** Detect free variable `global` from Node.js. */
+  var freeGlobal = checkGlobal(typeof global == 'object' && global);
+
+  /** Detect free variable `self`. */
+  var freeSelf = checkGlobal(typeof self == 'object' && self);
+
+  /** Detect `this` as the global object. */
+  var thisGlobal = checkGlobal(typeof this == 'object' && this);
+
+  /** Used as a reference to the global object. */
+  var root = freeGlobal || freeSelf || thisGlobal || Function('return this')();
+
+  /** Built-in value references. */
+  var Symbol$1 = root.Symbol;
+
+  /** Used as references for various `Number` constants. */
+  var INFINITY$1 = 1 / 0;
+
+  /** Used to convert symbols to primitives and strings. */
+  var symbolProto = Symbol$1 ? Symbol$1.prototype : undefined;
+  var symbolToString = symbolProto ? symbolProto.toString : undefined;
+  /**
+   * The base implementation of `_.toString` which doesn't convert nullish
+   * values to empty strings.
+   *
+   * @private
+   * @param {*} value The value to process.
+   * @returns {string} Returns the string.
+   */
+  function baseToString(value) {
+    // Exit early for strings to avoid a performance hit in some environments.
+    if (typeof value == 'string') {
+      return value;
     }
+    if (isSymbol(value)) {
+      return symbolToString ? symbolToString.call(value) : '';
+    }
+    var result = (value + '');
+    return (result == '0' && (1 / value) == -INFINITY$1) ? '-0' : result;
+  }
+
+  /**
+   * The base implementation of `_.slice` without an iteratee call guard.
+   *
+   * @private
+   * @param {Array} array The array to slice.
+   * @param {number} [start=0] The start position.
+   * @param {number} [end=array.length] The end position.
+   * @returns {Array} Returns the slice of `array`.
+   */
+  function baseSlice(array, start, end) {
+    var index = -1,
+        length = array.length;
+
+    if (start < 0) {
+      start = -start > length ? 0 : (length + start);
+    }
+    end = end > length ? length : end;
+    if (end < 0) {
+      end += length;
+    }
+    length = start > end ? 0 : ((end - start) >>> 0);
+    start >>>= 0;
+
+    var result = Array(length);
+    while (++index < length) {
+      result[index] = array[index + start];
+    }
+    return result;
+  }
+
+  /**
+   * Casts `array` to a slice if it's needed.
+   *
+   * @private
+   * @param {Array} array The array to inspect.
+   * @param {number} start The start position.
+   * @param {number} [end=array.length] The end position.
+   * @returns {Array} Returns the cast slice.
+   */
+  function castSlice(array, start, end) {
+    var length = array.length;
+    end = end === undefined ? length : end;
+    return (!start && end >= length) ? array : baseSlice(array, start, end);
+  }
+
+  /**
+   * Used by `_.trim` and `_.trimEnd` to get the index of the last string symbol
+   * that is not found in the character symbols.
+   *
+   * @private
+   * @param {Array} strSymbols The string symbols to inspect.
+   * @param {Array} chrSymbols The character symbols to find.
+   * @returns {number} Returns the index of the last unmatched string symbol.
+   */
+  function charsEndIndex(strSymbols, chrSymbols) {
+    var index = strSymbols.length;
+
+    while (index-- && baseIndexOf(chrSymbols, strSymbols[index], 0) > -1) {}
+    return index;
+  }
+
+  /**
+   * Used by `_.trim` and `_.trimStart` to get the index of the first string symbol
+   * that is not found in the character symbols.
+   *
+   * @private
+   * @param {Array} strSymbols The string symbols to inspect.
+   * @param {Array} chrSymbols The character symbols to find.
+   * @returns {number} Returns the index of the first unmatched string symbol.
+   */
+  function charsStartIndex(strSymbols, chrSymbols) {
+    var index = -1,
+        length = strSymbols.length;
+
+    while (++index < length && baseIndexOf(chrSymbols, strSymbols[index], 0) > -1) {}
+    return index;
+  }
+
+  /** Used to compose unicode character classes. */
+  var rsAstralRange = '\\ud800-\\udfff';
+  var rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23';
+  var rsComboSymbolsRange = '\\u20d0-\\u20f0';
+  var rsVarRange = '\\ufe0e\\ufe0f';
+  var rsAstral = '[' + rsAstralRange + ']';
+  var rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']';
+  var rsFitz = '\\ud83c[\\udffb-\\udfff]';
+  var rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')';
+  var rsNonAstral = '[^' + rsAstralRange + ']';
+  var rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}';
+  var rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]';
+  var rsZWJ = '\\u200d';
+  var reOptMod = rsModifier + '?';
+  var rsOptVar = '[' + rsVarRange + ']?';
+  var rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*';
+  var rsSeq = rsOptVar + reOptMod + rsOptJoin;
+  var rsSymbol = '(?:' + [rsNonAstral + rsCombo + '?', rsCombo, rsRegional, rsSurrPair, rsAstral].join('|') + ')';
+  /** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
+  var reComplexSymbol = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq, 'g');
+
+  /**
+   * Converts `string` to an array.
+   *
+   * @private
+   * @param {string} string The string to convert.
+   * @returns {Array} Returns the converted array.
+   */
+  function stringToArray(string) {
+    return string.match(reComplexSymbol);
+  }
+
+  /**
+   * Converts `value` to a string. An empty string is returned for `null`
+   * and `undefined` values. The sign of `-0` is preserved.
+   *
+   * @static
+   * @memberOf _
+   * @since 4.0.0
+   * @category Lang
+   * @param {*} value The value to process.
+   * @returns {string} Returns the string.
+   * @example
+   *
+   * _.toString(null);
+   * // => ''
+   *
+   * _.toString(-0);
+   * // => '-0'
+   *
+   * _.toString([1, 2, 3]);
+   * // => '1,2,3'
+   */
+  function toString(value) {
+    return value == null ? '' : baseToString(value);
+  }
+
+  /** Used to match leading and trailing whitespace. */
+  var reTrim$1 = /^\s+|\s+$/g;
+
+  /**
+   * Removes leading and trailing whitespace or specified characters from `string`.
+   *
+   * @static
+   * @memberOf _
+   * @since 3.0.0
+   * @category String
+   * @param {string} [string=''] The string to trim.
+   * @param {string} [chars=whitespace] The characters to trim.
+   * @param- {Object} [guard] Enables use as an iteratee for methods like `_.map`.
+   * @returns {string} Returns the trimmed string.
+   * @example
+   *
+   * _.trim('  abc  ');
+   * // => 'abc'
+   *
+   * _.trim('-_-abc-_-', '_-');
+   * // => 'abc'
+   *
+   * _.map(['  foo  ', '  bar  '], _.trim);
+   * // => ['foo', 'bar']
+   */
+  function trim(string, chars, guard) {
+    string = toString(string);
+    if (string && (guard || chars === undefined)) {
+      return string.replace(reTrim$1, '');
+    }
+    if (!string || !(chars = baseToString(chars))) {
+      return string;
+    }
+    var strSymbols = stringToArray(string),
+        chrSymbols = stringToArray(chars),
+        start = charsStartIndex(strSymbols, chrSymbols),
+        end = charsEndIndex(strSymbols, chrSymbols) + 1;
+
+    return castSlice(strSymbols, start, end).join('');
+  }
+
+  var FN_ARGS = /^(function)?\s*[^\(]*\(\s*([^\)]*)\)/m;
+  var FN_ARG_SPLIT = /,/;
+  var FN_ARG = /(=.+)?(\s*)$/;
+  var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
+
+  function parseParams(func) {
+      func = func.toString().replace(STRIP_COMMENTS, '');
+      func = func.match(FN_ARGS)[2].replace(' ', '');
+      func = func ? func.split(FN_ARG_SPLIT) : [];
+      func = func.map(function (arg) {
+          return trim(arg.replace(FN_ARG, ''));
+      });
+      return func;
+  }
+
+  /**
+   * A dependency-injected version of the [async.auto]{@link module:ControlFlow.auto} function. Dependent
+   * tasks are specified as parameters to the function, after the usual callback
+   * parameter, with the parameter names matching the names of the tasks it
+   * depends on. This can provide even more readable task graphs which can be
+   * easier to maintain.
+   *
+   * If a final callback is specified, the task results are similarly injected,
+   * specified as named parameters after the initial error parameter.
+   *
+   * The autoInject function is purely syntactic sugar and its semantics are
+   * otherwise equivalent to [async.auto]{@link module:ControlFlow.auto}.
+   *
+   * @name autoInject
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.auto]{@link module:ControlFlow.auto}
+   * @category Control Flow
+   * @param {Object} tasks - An object, each of whose properties is a function of
+   * the form 'func([dependencies...], callback). The object's key of a property
+   * serves as the name of the task defined by that property, i.e. can be used
+   * when specifying requirements for other tasks.
+   * * The `callback` parameter is a `callback(err, result)` which must be called
+   *   when finished, passing an `error` (which can be `null`) and the result of
+   *   the function's execution. The remaining parameters name other tasks on
+   *   which the task is dependent, and the results from those tasks are the
+   *   arguments of those parameters.
+   * @param {Function} [callback] - An optional callback which is called when all
+   * the tasks have been completed. It receives the `err` argument if any `tasks`
+   * pass an error to their callback. The remaining parameters are task names
+   * whose results you are interested in. This callback will only be called when
+   * all tasks have finished or an error has occurred, and so do not specify
+   * dependencies in the same way as `tasks` do. If an error occurs, no further
+   * `tasks` will be performed, and `results` will only be valid for those tasks
+   * which managed to complete. Invoked with (err, [results...]).
+   * @example
+   *
+   * //  The example from `auto` can be rewritten as follows:
+   * async.autoInject({
+   *     get_data: function(callback) {
+   *         // async code to get some data
+   *         callback(null, 'data', 'converted to array');
+   *     },
+   *     make_folder: function(callback) {
+   *         // async code to create a directory to store a file in
+   *         // this is run at the same time as getting the data
+   *         callback(null, 'folder');
+   *     },
+   *     write_file: function(get_data, make_folder, callback) {
+   *         // once there is some data and the directory exists,
+   *         // write the data to a file in the directory
+   *         callback(null, 'filename');
+   *     },
+   *     email_link: function(write_file, callback) {
+   *         // once the file is written let's email a link to it...
+   *         // write_file contains the filename returned by write_file.
+   *         callback(null, {'file':write_file, 'email':'user@example.com'});
+   *     }
+   * }, function(err, email_link) {
+   *     console.log('err = ', err);
+   *     console.log('email_link = ', email_link);
+   * });
+   *
+   * // If you are using a JS minifier that mangles parameter names, `autoInject`
+   * // will not work with plain functions, since the parameter names will be
+   * // collapsed to a single letter identifier.  To work around this, you can
+   * // explicitly specify the names of the parameters your task function needs
+   * // in an array, similar to Angular.js dependency injection.  The final
+   * // results callback can be provided as an array in the same way.
+   *
+   * // This still has an advantage over plain `auto`, since the results a task
+   * // depends on are still spread into arguments.
+   * async.autoInject({
+   *     //...
+   *     write_file: ['get_data', 'make_folder', function(get_data, make_folder, callback) {
+   *         callback(null, 'filename');
+   *     }],
+   *     email_link: ['write_file', function(write_file, callback) {
+   *         callback(null, {'file':write_file, 'email':'user@example.com'});
+   *     }]
+   *     //...
+   * }, ['email_link', function(err, email_link) {
+   *     console.log('err = ', err);
+   *     console.log('email_link = ', email_link);
+   * }]);
+   */
+  function autoInject(tasks, callback) {
+      var newTasks = {};
+
+      baseForOwn(tasks, function (taskFn, key) {
+          var params;
+
+          if (isArray(taskFn)) {
+              params = copyArray(taskFn);
+              taskFn = params.pop();
+
+              newTasks[key] = params.concat(params.length > 0 ? newTask : taskFn);
+          } else if (taskFn.length === 1) {
+              // no dependencies, use the function as-is
+              newTasks[key] = taskFn;
+          } else {
+              params = parseParams(taskFn);
+              if (taskFn.length === 0 && params.length === 0) {
+                  throw new Error("autoInject task functions require explicit parameters.");
+              }
+
+              params.pop();
+
+              newTasks[key] = params.concat(newTask);
+          }
 
-    /**
-     * Creates a stack cache object to store key-value pairs.
-     *
-     * @private
-     * @constructor
-     * @param {Array} [entries] The key-value pairs to cache.
-     */
-    function Stack(entries) {
-      this.__data__ = new ListCache(entries);
-    }
+          function newTask(results, taskCb) {
+              var newArgs = arrayMap(params, function (name) {
+                  return results[name];
+              });
+              newArgs.push(taskCb);
+              taskFn.apply(null, newArgs);
+          }
+      });
 
-    // Add methods to `Stack`.
-    Stack.prototype.clear = stackClear;
-    Stack.prototype['delete'] = stackDelete;
-    Stack.prototype.get = stackGet;
-    Stack.prototype.has = stackHas;
-    Stack.prototype.set = stackSet;
-
-    /** Used to stand-in for `undefined` hash values. */
-    var HASH_UNDEFINED$2 = '__lodash_hash_undefined__';
-
-    /**
-     * Adds `value` to the array cache.
-     *
-     * @private
-     * @name add
-     * @memberOf SetCache
-     * @alias push
-     * @param {*} value The value to cache.
-     * @returns {Object} Returns the cache instance.
-     */
-    function setCacheAdd(value) {
-      this.__data__.set(value, HASH_UNDEFINED$2);
-      return this;
-    }
+      auto(newTasks, callback);
+  }
 
-    /**
-     * Checks if `value` is in the array cache.
-     *
-     * @private
-     * @name has
-     * @memberOf SetCache
-     * @param {*} value The value to search for.
-     * @returns {number} Returns `true` if `value` is found, else `false`.
-     */
-    function setCacheHas(value) {
-      return this.__data__.has(value);
-    }
+  var hasSetImmediate = typeof setImmediate === 'function' && setImmediate;
+  var hasNextTick = typeof process === 'object' && typeof process.nextTick === 'function';
 
-    /**
-     *
-     * Creates an array cache object to store unique values.
-     *
-     * @private
-     * @constructor
-     * @param {Array} [values] The values to cache.
-     */
-    function SetCache(values) {
-      var index = -1,
-          length = values ? values.length : 0;
+  function fallback(fn) {
+      setTimeout(fn, 0);
+  }
 
-      this.__data__ = new MapCache;
-      while (++index < length) {
-        this.add(values[index]);
+  function wrap(defer) {
+      return rest(function (fn, args) {
+          defer(function () {
+              fn.apply(null, args);
+          });
+      });
+  }
+
+  var _defer;
+
+  if (hasSetImmediate) {
+      _defer = setImmediate;
+  } else if (hasNextTick) {
+      _defer = process.nextTick;
+  } else {
+      _defer = fallback;
+  }
+
+  var setImmediate$1 = wrap(_defer);
+
+  // Simple doubly linked list (https://en.wikipedia.org/wiki/Doubly_linked_list) implementation
+  // used for queues. This implementation assumes that the node provided by the user can be modified
+  // to adjust the next and last properties. We implement only the minimal functionality
+  // for queue support.
+  function DLL() {
+      this.head = this.tail = null;
+      this.length = 0;
+  }
+
+  function setInitial(dll, node) {
+      dll.length = 1;
+      dll.head = dll.tail = node;
+  }
+
+  DLL.prototype.removeLink = function (node) {
+      if (node.prev) node.prev.next = node.next;else this.head = node.next;
+      if (node.next) node.next.prev = node.prev;else this.tail = node.prev;
+
+      node.prev = node.next = null;
+      this.length -= 1;
+      return node;
+  };
+
+  DLL.prototype.empty = DLL;
+
+  DLL.prototype.insertAfter = function (node, newNode) {
+      newNode.prev = node;
+      newNode.next = node.next;
+      if (node.next) node.next.prev = newNode;else this.tail = newNode;
+      node.next = newNode;
+      this.length += 1;
+  };
+
+  DLL.prototype.insertBefore = function (node, newNode) {
+      newNode.prev = node.prev;
+      newNode.next = node;
+      if (node.prev) node.prev.next = newNode;else this.head = newNode;
+      node.prev = newNode;
+      this.length += 1;
+  };
+
+  DLL.prototype.unshift = function (node) {
+      if (this.head) this.insertBefore(this.head, node);else setInitial(this, node);
+  };
+
+  DLL.prototype.push = function (node) {
+      if (this.tail) this.insertAfter(this.tail, node);else setInitial(this, node);
+  };
+
+  DLL.prototype.shift = function () {
+      return this.head && this.removeLink(this.head);
+  };
+
+  DLL.prototype.pop = function () {
+      return this.tail && this.removeLink(this.tail);
+  };
+
+  function queue(worker, concurrency, payload) {
+      if (concurrency == null) {
+          concurrency = 1;
+      } else if (concurrency === 0) {
+          throw new Error('Concurrency must not be zero');
       }
-    }
-
-    // Add methods to `SetCache`.
-    SetCache.prototype.add = SetCache.prototype.push = setCacheAdd;
-    SetCache.prototype.has = setCacheHas;
-
-    /**
-     * A specialized version of `_.some` for arrays without support for iteratee
-     * shorthands.
-     *
-     * @private
-     * @param {Array} [array] The array to iterate over.
-     * @param {Function} predicate The function invoked per iteration.
-     * @returns {boolean} Returns `true` if any element passes the predicate check,
-     *  else `false`.
-     */
-    function arraySome(array, predicate) {
-      var index = -1,
-          length = array ? array.length : 0;
 
-      while (++index < length) {
-        if (predicate(array[index], index, array)) {
-          return true;
-        }
+      function _insert(data, pos, callback) {
+          if (callback != null && typeof callback !== 'function') {
+              throw new Error('task callback must be a function');
+          }
+          q.started = true;
+          if (!isArray(data)) {
+              data = [data];
+          }
+          if (data.length === 0 && q.idle()) {
+              // call drain immediately if there are no tasks
+              return setImmediate$1(function () {
+                  q.drain();
+              });
+          }
+          arrayEach(data, function (task) {
+              var item = {
+                  data: task,
+                  callback: callback || noop
+              };
+
+              if (pos) {
+                  q._tasks.unshift(item);
+              } else {
+                  q._tasks.push(item);
+              }
+          });
+          setImmediate$1(q.process);
       }
-      return false;
-    }
 
-    var UNORDERED_COMPARE_FLAG$1 = 1;
-    var PARTIAL_COMPARE_FLAG$2 = 2;
-    /**
-     * A specialized version of `baseIsEqualDeep` for arrays with support for
-     * partial deep comparisons.
-     *
-     * @private
-     * @param {Array} array The array to compare.
-     * @param {Array} other The other array to compare.
-     * @param {Function} equalFunc The function to determine equivalents of values.
-     * @param {Function} customizer The function to customize comparisons.
-     * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual`
-     *  for more details.
-     * @param {Object} stack Tracks traversed `array` and `other` objects.
-     * @returns {boolean} Returns `true` if the arrays are equivalent, else `false`.
-     */
-    function equalArrays(array, other, equalFunc, customizer, bitmask, stack) {
-      var isPartial = bitmask & PARTIAL_COMPARE_FLAG$2,
-          arrLength = array.length,
-          othLength = other.length;
-
-      if (arrLength != othLength && !(isPartial && othLength > arrLength)) {
-        return false;
+      function _next(tasks) {
+          return function () {
+              workers -= 1;
+
+              var removed = false;
+              var args = arguments;
+              arrayEach(tasks, function (task) {
+                  arrayEach(workersList, function (worker, index) {
+                      if (worker === task && !removed) {
+                          workersList.splice(index, 1);
+                          removed = true;
+                      }
+                  });
+
+                  task.callback.apply(task, args);
+
+                  if (args[0] != null) {
+                      q.error(args[0], task.data);
+                  }
+              });
+
+              if (workers <= q.concurrency - q.buffer) {
+                  q.unsaturated();
+              }
+
+              if (q._tasks.length + workers === 0) {
+                  q.drain();
+              }
+              q.process();
+          };
       }
-      // Assume cyclic values are equal.
-      var stacked = stack.get(array);
-      if (stacked) {
-        return stacked == other;
-      }
-      var index = -1,
-          result = true,
-          seen = (bitmask & UNORDERED_COMPARE_FLAG$1) ? new SetCache : undefined;
-
-      stack.set(array, other);
 
-      // Ignore non-index properties.
-      while (++index < arrLength) {
-        var arrValue = array[index],
-            othValue = other[index];
-
-        if (customizer) {
-          var compared = isPartial
-            ? customizer(othValue, arrValue, index, other, array, stack)
-            : customizer(arrValue, othValue, index, array, other, stack);
-        }
-        if (compared !== undefined) {
-          if (compared) {
-            continue;
+      var workers = 0;
+      var workersList = [];
+      var q = {
+          _tasks: new DLL(),
+          concurrency: concurrency,
+          payload: payload,
+          saturated: noop,
+          unsaturated: noop,
+          buffer: concurrency / 4,
+          empty: noop,
+          drain: noop,
+          error: noop,
+          started: false,
+          paused: false,
+          push: function (data, callback) {
+              _insert(data, false, callback);
+          },
+          kill: function () {
+              q.drain = noop;
+              q._tasks.empty();
+          },
+          unshift: function (data, callback) {
+              _insert(data, true, callback);
+          },
+          process: function () {
+              while (!q.paused && workers < q.concurrency && q._tasks.length) {
+                  var tasks = [],
+                      data = [];
+                  var l = q._tasks.length;
+                  if (q.payload) l = Math.min(l, q.payload);
+                  for (var i = 0; i < l; i++) {
+                      var node = q._tasks.shift();
+                      tasks.push(node);
+                      data.push(node.data);
+                  }
+
+                  if (q._tasks.length === 0) {
+                      q.empty();
+                  }
+                  workers += 1;
+                  workersList.push(tasks[0]);
+
+                  if (workers === q.concurrency) {
+                      q.saturated();
+                  }
+
+                  var cb = onlyOnce(_next(tasks));
+                  worker(data, cb);
+              }
+          },
+          length: function () {
+              return q._tasks.length;
+          },
+          running: function () {
+              return workers;
+          },
+          workersList: function () {
+              return workersList;
+          },
+          idle: function () {
+              return q._tasks.length + workers === 0;
+          },
+          pause: function () {
+              q.paused = true;
+          },
+          resume: function () {
+              if (q.paused === false) {
+                  return;
+              }
+              q.paused = false;
+              var resumeCount = Math.min(q.concurrency, q._tasks.length);
+              // Need to call q.process once per concurrent
+              // worker to preserve full concurrency after pause
+              for (var w = 1; w <= resumeCount; w++) {
+                  setImmediate$1(q.process);
+              }
           }
-          result = false;
-          break;
-        }
-        // Recursively compare arrays (susceptible to call stack limits).
-        if (seen) {
-          if (!arraySome(other, function(othValue, othIndex) {
-                if (!seen.has(othIndex) &&
-                    (arrValue === othValue || equalFunc(arrValue, othValue, customizer, bitmask, stack))) {
-                  return seen.add(othIndex);
-                }
-              })) {
-            result = false;
-            break;
+      };
+      return q;
+  }
+
+  /**
+   * A cargo of tasks for the worker function to complete. Cargo inherits all of
+   * the same methods and event callbacks as [`queue`]{@link module:ControlFlow.queue}.
+   * @typedef {Object} CargoObject
+   * @memberOf module:ControlFlow
+   * @property {Function} length - A function returning the number of items
+   * waiting to be processed. Invoke like `cargo.length()`.
+   * @property {number} payload - An `integer` for determining how many tasks
+   * should be process per round. This property can be changed after a `cargo` is
+   * created to alter the payload on-the-fly.
+   * @property {Function} push - Adds `task` to the `queue`. The callback is
+   * called once the `worker` has finished processing the task. Instead of a
+   * single task, an array of `tasks` can be submitted. The respective callback is
+   * used for every task in the list. Invoke like `cargo.push(task, [callback])`.
+   * @property {Function} saturated - A callback that is called when the
+   * `queue.length()` hits the concurrency and further tasks will be queued.
+   * @property {Function} empty - A callback that is called when the last item
+   * from the `queue` is given to a `worker`.
+   * @property {Function} drain - A callback that is called when the last item
+   * from the `queue` has returned from the `worker`.
+   * @property {Function} idle - a function returning false if there are items
+   * waiting or being processed, or true if not. Invoke like `cargo.idle()`.
+   * @property {Function} pause - a function that pauses the processing of tasks
+   * until `resume()` is called. Invoke like `cargo.pause()`.
+   * @property {Function} resume - a function that resumes the processing of
+   * queued tasks when the queue is paused. Invoke like `cargo.resume()`.
+   * @property {Function} kill - a function that removes the `drain` callback and
+   * empties remaining tasks from the queue forcing it to go idle. Invoke like `cargo.kill()`.
+   */
+
+  /**
+   * Creates a `cargo` object with the specified payload. Tasks added to the
+   * cargo will be processed altogether (up to the `payload` limit). If the
+   * `worker` is in progress, the task is queued until it becomes available. Once
+   * the `worker` has completed some tasks, each callback of those tasks is
+   * called. Check out [these](https://camo.githubusercontent.com/6bbd36f4cf5b35a0f11a96dcd2e97711ffc2fb37/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313637363837312f36383130382f62626330636662302d356632392d313165322d393734662d3333393763363464633835382e676966) [animations](https://camo.githubusercontent.com/f4810e00e1c5f5f8addbe3e9f49064fd5d102699/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313637363837312f36383130312f38346339323036362d356632392d313165322d383134662d3964336430323431336266642e676966)
+   * for how `cargo` and `queue` work.
+   *
+   * While [`queue`]{@link module:ControlFlow.queue} passes only one task to one of a group of workers
+   * at a time, cargo passes an array of tasks to a single worker, repeating
+   * when the worker is finished.
+   *
+   * @name cargo
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.queue]{@link module:ControlFlow.queue}
+   * @category Control Flow
+   * @param {Function} worker - An asynchronous function for processing an array
+   * of queued tasks, which must call its `callback(err)` argument when finished,
+   * with an optional `err` argument. Invoked with `(tasks, callback)`.
+   * @param {number} [payload=Infinity] - An optional `integer` for determining
+   * how many tasks should be processed per round; if omitted, the default is
+   * unlimited.
+   * @returns {module:ControlFlow.CargoObject} A cargo object to manage the tasks. Callbacks can
+   * attached as certain properties to listen for specific events during the
+   * lifecycle of the cargo and inner queue.
+   * @example
+   *
+   * // create a cargo object with payload 2
+   * var cargo = async.cargo(function(tasks, callback) {
+   *     for (var i=0; i<tasks.length; i++) {
+   *         console.log('hello ' + tasks[i].name);
+   *     }
+   *     callback();
+   * }, 2);
+   *
+   * // add some items
+   * cargo.push({name: 'foo'}, function(err) {
+   *     console.log('finished processing foo');
+   * });
+   * cargo.push({name: 'bar'}, function(err) {
+   *     console.log('finished processing bar');
+   * });
+   * cargo.push({name: 'baz'}, function(err) {
+   *     console.log('finished processing baz');
+   * });
+   */
+  function cargo(worker, payload) {
+    return queue(worker, 1, payload);
+  }
+
+  /**
+   * The same as [`eachOf`]{@link module:Collections.eachOf} but runs a maximum of `limit` async operations at a
+   * time.
+   *
+   * @name eachOfLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.eachOf]{@link module:Collections.eachOf}
+   * @alias forEachOfLimit
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A function to apply to each
+   * item in `coll`. The `key` is the item's key, or index in the case of an
+   * array. The iteratee is passed a `callback(err)` which must be called once it
+   * has completed. If no error has occurred, the callback should be run without
+   * arguments or with an explicit `null` argument. Invoked with
+   * (item, key, callback).
+   * @param {Function} [callback] - A callback which is called when all
+   * `iteratee` functions have finished, or an error occurs. Invoked with (err).
+   */
+  function eachOfLimit(coll, limit, iteratee, callback) {
+    _eachOfLimit(limit)(coll, iteratee, callback);
+  }
+
+  /**
+   * The same as [`eachOf`]{@link module:Collections.eachOf} but runs only a single async operation at a time.
+   *
+   * @name eachOfSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.eachOf]{@link module:Collections.eachOf}
+   * @alias forEachOfSeries
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each item in `coll`. The
+   * `key` is the item's key, or index in the case of an array. The iteratee is
+   * passed a `callback(err)` which must be called once it has completed. If no
+   * error has occurred, the callback should be run without arguments or with an
+   * explicit `null` argument. Invoked with (item, key, callback).
+   * @param {Function} [callback] - A callback which is called when all `iteratee`
+   * functions have finished, or an error occurs. Invoked with (err).
+   */
+  var eachOfSeries = doLimit(eachOfLimit, 1);
+
+  /**
+   * Reduces `coll` into a single value using an async `iteratee` to return each
+   * successive step. `memo` is the initial state of the reduction. This function
+   * only operates in series.
+   *
+   * For performance reasons, it may make sense to split a call to this function
+   * into a parallel map, and then use the normal `Array.prototype.reduce` on the
+   * results. This function is for situations where each step in the reduction
+   * needs to be async; if you can get the data before reducing it, then it's
+   * probably a good idea to do so.
+   *
+   * @name reduce
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @alias inject
+   * @alias foldl
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {*} memo - The initial state of the reduction.
+   * @param {Function} iteratee - A function applied to each item in the
+   * array to produce the next step in the reduction. The `iteratee` is passed a
+   * `callback(err, reduction)` which accepts an optional error as its first
+   * argument, and the state of the reduction as the second. If an error is
+   * passed to the callback, the reduction is stopped and the main `callback` is
+   * immediately called with the error. Invoked with (memo, item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Result is the reduced value. Invoked with
+   * (err, result).
+   * @example
+   *
+   * async.reduce([1,2,3], 0, function(memo, item, callback) {
+   *     // pointless async:
+   *     process.nextTick(function() {
+   *         callback(null, memo + item)
+   *     });
+   * }, function(err, result) {
+   *     // result is now equal to the last value of memo, which is 6
+   * });
+   */
+  function reduce(coll, memo, iteratee, callback) {
+      eachOfSeries(coll, function (x, i, callback) {
+          iteratee(memo, x, function (err, v) {
+              memo = v;
+              callback(err);
+          });
+      }, function (err) {
+          callback(err, memo);
+      });
+  }
+
+  /**
+   * Version of the compose function that is more natural to read. Each function
+   * consumes the return value of the previous function. It is the equivalent of
+   * [compose]{@link module:ControlFlow.compose} with the arguments reversed.
+   *
+   * Each function is executed with the `this` binding of the composed function.
+   *
+   * @name seq
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.compose]{@link module:ControlFlow.compose}
+   * @category Control Flow
+   * @param {...Function} functions - the asynchronous functions to compose
+   * @returns {Function} a function that composes the `functions` in order
+   * @example
+   *
+   * // Requires lodash (or underscore), express3 and dresende's orm2.
+   * // Part of an app, that fetches cats of the logged user.
+   * // This example uses `seq` function to avoid overnesting and error
+   * // handling clutter.
+   * app.get('/cats', function(request, response) {
+   *     var User = request.models.User;
+   *     async.seq(
+   *         _.bind(User.get, User),  // 'User.get' has signature (id, callback(err, data))
+   *         function(user, fn) {
+   *             user.getCats(fn);      // 'getCats' has signature (callback(err, data))
+   *         }
+   *     )(req.session.user_id, function (err, cats) {
+   *         if (err) {
+   *             console.error(err);
+   *             response.json({ status: 'error', message: err.message });
+   *         } else {
+   *             response.json({ status: 'ok', message: 'Cats found', data: cats });
+   *         }
+   *     });
+   * });
+   */
+  var seq = rest(function seq(functions) {
+      return rest(function (args) {
+          var that = this;
+
+          var cb = args[args.length - 1];
+          if (typeof cb == 'function') {
+              args.pop();
+          } else {
+              cb = noop;
           }
-        } else if (!(
-              arrValue === othValue ||
-                equalFunc(arrValue, othValue, customizer, bitmask, stack)
-            )) {
-          result = false;
-          break;
-        }
-      }
-      stack['delete'](array);
-      return result;
-    }
-
-    /** Built-in value references. */
-    var Symbol$1 = root.Symbol;
 
-    /** Built-in value references. */
-    var Uint8Array = root.Uint8Array;
-
-    /**
-     * Converts `map` to its key-value pairs.
-     *
-     * @private
-     * @param {Object} map The map to convert.
-     * @returns {Array} Returns the key-value pairs.
-     */
-    function mapToArray(map) {
-      var index = -1,
-          result = Array(map.size);
-
-      map.forEach(function(value, key) {
-        result[++index] = [key, value];
+          reduce(functions, args, function (newargs, fn, cb) {
+              fn.apply(that, newargs.concat([rest(function (err, nextargs) {
+                  cb(err, nextargs);
+              })]));
+          }, function (err, results) {
+              cb.apply(that, [err].concat(results));
+          });
       });
-      return result;
-    }
-
-    /**
-     * Converts `set` to an array of its values.
-     *
-     * @private
-     * @param {Object} set The set to convert.
-     * @returns {Array} Returns the values.
-     */
-    function setToArray(set) {
-      var index = -1,
-          result = Array(set.size);
-
-      set.forEach(function(value) {
-        result[++index] = value;
+  });
+
+  var reverse = Array.prototype.reverse;
+
+  /**
+   * Creates a function which is a composition of the passed asynchronous
+   * functions. Each function consumes the return value of the function that
+   * follows. Composing functions `f()`, `g()`, and `h()` would produce the result
+   * of `f(g(h()))`, only this version uses callbacks to obtain the return values.
+   *
+   * Each function is executed with the `this` binding of the composed function.
+   *
+   * @name compose
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {...Function} functions - the asynchronous functions to compose
+   * @returns {Function} an asynchronous function that is the composed
+   * asynchronous `functions`
+   * @example
+   *
+   * function add1(n, callback) {
+   *     setTimeout(function () {
+   *         callback(null, n + 1);
+   *     }, 10);
+   * }
+   *
+   * function mul3(n, callback) {
+   *     setTimeout(function () {
+   *         callback(null, n * 3);
+   *     }, 10);
+   * }
+   *
+   * var add1mul3 = async.compose(mul3, add1);
+   * add1mul3(4, function (err, result) {
+   *     // result now equals 15
+   * });
+   */
+  function compose() /* functions... */{
+    return seq.apply(null, reverse.call(arguments));
+  }
+
+  function concat$1(eachfn, arr, fn, callback) {
+      var result = [];
+      eachfn(arr, function (x, index, cb) {
+          fn(x, function (err, y) {
+              result = result.concat(y || []);
+              cb(err);
+          });
+      }, function (err) {
+          callback(err, result);
       });
-      return result;
-    }
-
-    var UNORDERED_COMPARE_FLAG$2 = 1;
-    var PARTIAL_COMPARE_FLAG$3 = 2;
-    var boolTag = '[object Boolean]';
-    var dateTag = '[object Date]';
-    var errorTag = '[object Error]';
-    var mapTag = '[object Map]';
-    var numberTag = '[object Number]';
-    var regexpTag = '[object RegExp]';
-    var setTag = '[object Set]';
-    var stringTag$1 = '[object String]';
-    var symbolTag$1 = '[object Symbol]';
-    var arrayBufferTag = '[object ArrayBuffer]';
-    var dataViewTag = '[object DataView]';
-    var symbolProto = Symbol$1 ? Symbol$1.prototype : undefined;
-    var symbolValueOf = symbolProto ? symbolProto.valueOf : undefined;
-    /**
-     * A specialized version of `baseIsEqualDeep` for comparing objects of
-     * the same `toStringTag`.
-     *
-     * **Note:** This function only supports comparing values with tags of
-     * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`.
-     *
-     * @private
-     * @param {Object} object The object to compare.
-     * @param {Object} other The other object to compare.
-     * @param {string} tag The `toStringTag` of the objects to compare.
-     * @param {Function} equalFunc The function to determine equivalents of values.
-     * @param {Function} customizer The function to customize comparisons.
-     * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual`
-     *  for more details.
-     * @param {Object} stack Tracks traversed `object` and `other` objects.
-     * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
-     */
-    function equalByTag(object, other, tag, equalFunc, customizer, bitmask, stack) {
-      switch (tag) {
-        case dataViewTag:
-          if ((object.byteLength != other.byteLength) ||
-              (object.byteOffset != other.byteOffset)) {
-            return false;
+  }
+
+  /**
+   * Like [`each`]{@link module:Collections.each}, except that it passes the key (or index) as the second argument
+   * to the iteratee.
+   *
+   * @name eachOf
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @alias forEachOf
+   * @category Collection
+   * @see [async.each]{@link module:Collections.each}
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each
+   * item in `coll`. The `key` is the item's key, or index in the case of an
+   * array. The iteratee is passed a `callback(err)` which must be called once it
+   * has completed. If no error has occurred, the callback should be run without
+   * arguments or with an explicit `null` argument. Invoked with
+   * (item, key, callback).
+   * @param {Function} [callback] - A callback which is called when all
+   * `iteratee` functions have finished, or an error occurs. Invoked with (err).
+   * @example
+   *
+   * var obj = {dev: "/dev.json", test: "/test.json", prod: "/prod.json"};
+   * var configs = {};
+   *
+   * async.forEachOf(obj, function (value, key, callback) {
+   *     fs.readFile(__dirname + value, "utf8", function (err, data) {
+   *         if (err) return callback(err);
+   *         try {
+   *             configs[key] = JSON.parse(data);
+   *         } catch (e) {
+   *             return callback(e);
+   *         }
+   *         callback();
+   *     });
+   * }, function (err) {
+   *     if (err) console.error(err.message);
+   *     // configs is now a map of JSON data
+   *     doSomethingWith(configs);
+   * });
+   */
+  var eachOf = doLimit(eachOfLimit, Infinity);
+
+  function doParallel(fn) {
+      return function (obj, iteratee, callback) {
+          return fn(eachOf, obj, iteratee, callback);
+      };
+  }
+
+  /**
+   * Applies `iteratee` to each item in `coll`, concatenating the results. Returns
+   * the concatenated list. The `iteratee`s are called in parallel, and the
+   * results are concatenated as they return. There is no guarantee that the
+   * results array will be returned in the original order of `coll` passed to the
+   * `iteratee` function.
+   *
+   * @name concat
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, results)` which must be called once
+   * it has completed with an error (which can be `null`) and an array of results.
+   * Invoked with (item, callback).
+   * @param {Function} [callback(err)] - A callback which is called after all the
+   * `iteratee` functions have finished, or an error occurs. Results is an array
+   * containing the concatenated results of the `iteratee` function. Invoked with
+   * (err, results).
+   * @example
+   *
+   * async.concat(['dir1','dir2','dir3'], fs.readdir, function(err, files) {
+   *     // files is now a list of filenames that exist in the 3 directories
+   * });
+   */
+  var concat = doParallel(concat$1);
+
+  function doSeries(fn) {
+      return function (obj, iteratee, callback) {
+          return fn(eachOfSeries, obj, iteratee, callback);
+      };
+  }
+
+  /**
+   * The same as [`concat`]{@link module:Collections.concat} but runs only a single async operation at a time.
+   *
+   * @name concatSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.concat]{@link module:Collections.concat}
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, results)` which must be called once
+   * it has completed with an error (which can be `null`) and an array of results.
+   * Invoked with (item, callback).
+   * @param {Function} [callback(err)] - A callback which is called after all the
+   * `iteratee` functions have finished, or an error occurs. Results is an array
+   * containing the concatenated results of the `iteratee` function. Invoked with
+   * (err, results).
+   */
+  var concatSeries = doSeries(concat$1);
+
+  /**
+   * Returns a function that when called, calls-back with the values provided.
+   * Useful as the first function in a [`waterfall`]{@link module:ControlFlow.waterfall}, or for plugging values in to
+   * [`auto`]{@link module:ControlFlow.auto}.
+   *
+   * @name constant
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {...*} arguments... - Any number of arguments to automatically invoke
+   * callback with.
+   * @returns {Function} Returns a function that when invoked, automatically
+   * invokes the callback with the previous given arguments.
+   * @example
+   *
+   * async.waterfall([
+   *     async.constant(42),
+   *     function (value, next) {
+   *         // value === 42
+   *     },
+   *     //...
+   * ], callback);
+   *
+   * async.waterfall([
+   *     async.constant(filename, "utf8"),
+   *     fs.readFile,
+   *     function (fileData, next) {
+   *         //...
+   *     }
+   *     //...
+   * ], callback);
+   *
+   * async.auto({
+   *     hostname: async.constant("https://server.net/"),
+   *     port: findFreePort,
+   *     launchServer: ["hostname", "port", function (options, cb) {
+   *         startServer(options, cb);
+   *     }],
+   *     //...
+   * }, callback);
+   */
+  var constant = rest(function (values) {
+      var args = [null].concat(values);
+      return initialParams(function (ignoredArgs, callback) {
+          return callback.apply(this, args);
+      });
+  });
+
+  /**
+   * This method returns the first argument given to it.
+   *
+   * @static
+   * @since 0.1.0
+   * @memberOf _
+   * @category Util
+   * @param {*} value Any value.
+   * @returns {*} Returns `value`.
+   * @example
+   *
+   * var object = { 'user': 'fred' };
+   *
+   * console.log(_.identity(object) === object);
+   * // => true
+   */
+  function identity(value) {
+    return value;
+  }
+
+  function _createTester(eachfn, check, getResult) {
+      return function (arr, limit, iteratee, cb) {
+          function done(err) {
+              if (cb) {
+                  if (err) {
+                      cb(err);
+                  } else {
+                      cb(null, getResult(false));
+                  }
+              }
           }
-          object = object.buffer;
-          other = other.buffer;
-
-        case arrayBufferTag:
-          if ((object.byteLength != other.byteLength) ||
-              !equalFunc(new Uint8Array(object), new Uint8Array(other))) {
-            return false;
+          function wrappedIteratee(x, _, callback) {
+              if (!cb) return callback();
+              iteratee(x, function (err, v) {
+                  if (cb) {
+                      if (err) {
+                          cb(err);
+                          cb = iteratee = false;
+                      } else if (check(v)) {
+                          cb(null, getResult(true, x));
+                          cb = iteratee = false;
+                      }
+                  }
+                  callback();
+              });
           }
-          return true;
-
-        case boolTag:
-        case dateTag:
-          // Coerce dates and booleans to numbers, dates to milliseconds and
-          // booleans to `1` or `0` treating invalid dates coerced to `NaN` as
-          // not equal.
-          return +object == +other;
-
-        case errorTag:
-          return object.name == other.name && object.message == other.message;
-
-        case numberTag:
-          // Treat `NaN` vs. `NaN` as equal.
-          return (object != +object) ? other != +other : object == +other;
-
-        case regexpTag:
-        case stringTag$1:
-          // Coerce regexes to strings and treat strings, primitives and objects,
-          // as equal. See http://www.ecma-international.org/ecma-262/6.0/#sec-regexp.prototype.tostring
-          // for more details.
-          return object == (other + '');
-
-        case mapTag:
-          var convert = mapToArray;
-
-        case setTag:
-          var isPartial = bitmask & PARTIAL_COMPARE_FLAG$3;
-          convert || (convert = setToArray);
-
-          if (object.size != other.size && !isPartial) {
-            return false;
+          if (arguments.length > 3) {
+              cb = cb || noop;
+              eachfn(arr, limit, wrappedIteratee, done);
+          } else {
+              cb = iteratee;
+              cb = cb || noop;
+              iteratee = limit;
+              eachfn(arr, wrappedIteratee, done);
           }
-          // Assume cyclic values are equal.
-          var stacked = stack.get(object);
-          if (stacked) {
-            return stacked == other;
+      };
+  }
+
+  function _findGetResult(v, x) {
+      return x;
+  }
+
+  /**
+   * Returns the first value in `coll` that passes an async truth test. The
+   * `iteratee` is applied in parallel, meaning the first iteratee to return
+   * `true` will fire the detect `callback` with that result. That means the
+   * result might not be the first item in the original `coll` (in terms of order)
+   * that passes the test.
+
+   * If order within the original `coll` is important, then look at
+   * [`detectSeries`]{@link module:Collections.detectSeries}.
+   *
+   * @name detect
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @alias find
+   * @category Collections
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, truthValue)` which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called as soon as any
+   * iteratee returns `true`, or after all the `iteratee` functions have finished.
+   * Result will be the first item in the array that passes the truth test
+   * (iteratee) or the value `undefined` if none passed. Invoked with
+   * (err, result).
+   * @example
+   *
+   * async.detect(['file1','file2','file3'], function(filePath, callback) {
+   *     fs.access(filePath, function(err) {
+   *         callback(null, !err)
+   *     });
+   * }, function(err, result) {
+   *     // result now equals the first file in the list that exists
+   * });
+   */
+  var detect = _createTester(eachOf, identity, _findGetResult);
+
+  /**
+   * The same as [`detect`]{@link module:Collections.detect} but runs a maximum of `limit` async operations at a
+   * time.
+   *
+   * @name detectLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.detect]{@link module:Collections.detect}
+   * @alias findLimit
+   * @category Collections
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, truthValue)` which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called as soon as any
+   * iteratee returns `true`, or after all the `iteratee` functions have finished.
+   * Result will be the first item in the array that passes the truth test
+   * (iteratee) or the value `undefined` if none passed. Invoked with
+   * (err, result).
+   */
+  var detectLimit = _createTester(eachOfLimit, identity, _findGetResult);
+
+  /**
+   * The same as [`detect`]{@link module:Collections.detect} but runs only a single async operation at a time.
+   *
+   * @name detectSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.detect]{@link module:Collections.detect}
+   * @alias findSeries
+   * @category Collections
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, truthValue)` which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called as soon as any
+   * iteratee returns `true`, or after all the `iteratee` functions have finished.
+   * Result will be the first item in the array that passes the truth test
+   * (iteratee) or the value `undefined` if none passed. Invoked with
+   * (err, result).
+   */
+  var detectSeries = _createTester(eachOfSeries, identity, _findGetResult);
+
+  function consoleFunc(name) {
+      return rest(function (fn, args) {
+          fn.apply(null, args.concat([rest(function (err, args) {
+              if (typeof console === 'object') {
+                  if (err) {
+                      if (console.error) {
+                          console.error(err);
+                      }
+                  } else if (console[name]) {
+                      arrayEach(args, function (x) {
+                          console[name](x);
+                      });
+                  }
+              }
+          })]));
+      });
+  }
+
+  /**
+   * Logs the result of an `async` function to the `console` using `console.dir`
+   * to display the properties of the resulting object. Only works in Node.js or
+   * in browsers that support `console.dir` and `console.error` (such as FF and
+   * Chrome). If multiple arguments are returned from the async function,
+   * `console.dir` is called on each argument in order.
+   *
+   * @name dir
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {Function} function - The function you want to eventually apply all
+   * arguments to.
+   * @param {...*} arguments... - Any number of arguments to apply to the function.
+   * @example
+   *
+   * // in a module
+   * var hello = function(name, callback) {
+   *     setTimeout(function() {
+   *         callback(null, {hello: name});
+   *     }, 1000);
+   * };
+   *
+   * // in the node repl
+   * node> async.dir(hello, 'world');
+   * {hello: 'world'}
+   */
+  var dir = consoleFunc('dir');
+
+  /**
+   * Like [`whilst`]{@link module:ControlFlow.whilst}, except the `test` is an asynchronous function that
+   * is passed a callback in the form of `function (err, truth)`. If error is
+   * passed to `test` or `fn`, the main callback is immediately called with the
+   * value of the error.
+   *
+   * @name during
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.whilst]{@link module:ControlFlow.whilst}
+   * @category Control Flow
+   * @param {Function} test - asynchronous truth test to perform before each
+   * execution of `fn`. Invoked with (callback).
+   * @param {Function} fn - A function which is called each time `test` passes.
+   * The function is passed a `callback(err)`, which must be called once it has
+   * completed with an optional `err` argument. Invoked with (callback).
+   * @param {Function} [callback] - A callback which is called after the test
+   * function has failed and repeated execution of `fn` has stopped. `callback`
+   * will be passed an error and any arguments passed to the final `fn`'s
+   * callback. Invoked with (err, [results]);
+   * @example
+   *
+   * var count = 0;
+   *
+   * async.during(
+   *     function (callback) {
+   *         return callback(null, count < 5);
+   *     },
+   *     function (callback) {
+   *         count++;
+   *         setTimeout(callback, 1000);
+   *     },
+   *     function (err) {
+   *         // 5 seconds have passed
+   *     }
+   * );
+   */
+  function during(test, fn, callback) {
+      callback = callback || noop;
+
+      var next = rest(function (err, args) {
+          if (err) {
+              callback(err);
+          } else {
+              args.push(check);
+              test.apply(this, args);
           }
-          bitmask |= UNORDERED_COMPARE_FLAG$2;
-          stack.set(object, other);
+      });
 
-          // Recursively compare objects (susceptible to call stack limits).
-          return equalArrays(convert(object), convert(other), equalFunc, customizer, bitmask, stack);
+      var check = function (err, truth) {
+          if (err) return callback(err);
+          if (!truth) return callback(null);
+          fn(next);
+      };
 
-        case symbolTag$1:
-          if (symbolValueOf) {
-            return symbolValueOf.call(object) == symbolValueOf.call(other);
+      test(check);
+  }
+
+  /**
+   * The post-check version of [`during`]{@link module:ControlFlow.during}. To reflect the difference in
+   * the order of operations, the arguments `test` and `fn` are switched.
+   *
+   * Also a version of [`doWhilst`]{@link module:ControlFlow.doWhilst} with asynchronous `test` function.
+   * @name doDuring
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.during]{@link module:ControlFlow.during}
+   * @category Control Flow
+   * @param {Function} fn - A function which is called each time `test` passes.
+   * The function is passed a `callback(err)`, which must be called once it has
+   * completed with an optional `err` argument. Invoked with (callback).
+   * @param {Function} test - asynchronous truth test to perform before each
+   * execution of `fn`. Invoked with (callback).
+   * @param {Function} [callback] - A callback which is called after the test
+   * function has failed and repeated execution of `fn` has stopped. `callback`
+   * will be passed an error and any arguments passed to the final `fn`'s
+   * callback. Invoked with (err, [results]);
+   */
+  function doDuring(fn, test, callback) {
+      var calls = 0;
+
+      during(function (next) {
+          if (calls++ < 1) return next(null, true);
+          test.apply(this, arguments);
+      }, fn, callback);
+  }
+
+  /**
+   * Repeatedly call `fn`, while `test` returns `true`. Calls `callback` when
+   * stopped, or an error occurs.
+   *
+   * @name whilst
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Function} test - synchronous truth test to perform before each
+   * execution of `fn`. Invoked with ().
+   * @param {Function} iteratee - A function which is called each time `test` passes.
+   * The function is passed a `callback(err)`, which must be called once it has
+   * completed with an optional `err` argument. Invoked with (callback).
+   * @param {Function} [callback] - A callback which is called after the test
+   * function has failed and repeated execution of `fn` has stopped. `callback`
+   * will be passed an error and any arguments passed to the final `fn`'s
+   * callback. Invoked with (err, [results]);
+   * @returns undefined
+   * @example
+   *
+   * var count = 0;
+   * async.whilst(
+   *     function() { return count < 5; },
+   *     function(callback) {
+   *         count++;
+   *         setTimeout(function() {
+   *             callback(null, count);
+   *         }, 1000);
+   *     },
+   *     function (err, n) {
+   *         // 5 seconds have passed, n = 5
+   *     }
+   * );
+   */
+  function whilst(test, iteratee, callback) {
+      callback = callback || noop;
+      if (!test()) return callback(null);
+      var next = rest(function (err, args) {
+          if (err) return callback(err);
+          if (test.apply(this, args)) return iteratee(next);
+          callback.apply(null, [null].concat(args));
+      });
+      iteratee(next);
+  }
+
+  /**
+   * The post-check version of [`whilst`]{@link module:ControlFlow.whilst}. To reflect the difference in
+   * the order of operations, the arguments `test` and `fn` are switched.
+   *
+   * `doWhilst` is to `whilst` as `do while` is to `while` in plain JavaScript.
+   *
+   * @name doWhilst
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.whilst]{@link module:ControlFlow.whilst}
+   * @category Control Flow
+   * @param {Function} fn - A function which is called each time `test` passes.
+   * The function is passed a `callback(err)`, which must be called once it has
+   * completed with an optional `err` argument. Invoked with (callback).
+   * @param {Function} test - synchronous truth test to perform after each
+   * execution of `fn`. Invoked with Invoked with the non-error callback results
+   * of `fn`.
+   * @param {Function} [callback] - A callback which is called after the test
+   * function has failed and repeated execution of `fn` has stopped. `callback`
+   * will be passed an error and any arguments passed to the final `fn`'s
+   * callback. Invoked with (err, [results]);
+   */
+  function doWhilst(fn, test, callback) {
+      var calls = 0;
+      whilst(function () {
+          return ++calls <= 1 || test.apply(this, arguments);
+      }, fn, callback);
+  }
+
+  /**
+   * Like ['doWhilst']{@link module:ControlFlow.doWhilst}, except the `test` is inverted. Note the
+   * argument ordering differs from `until`.
+   *
+   * @name doUntil
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.doWhilst]{@link module:ControlFlow.doWhilst}
+   * @category Control Flow
+   * @param {Function} fn - A function which is called each time `test` fails.
+   * The function is passed a `callback(err)`, which must be called once it has
+   * completed with an optional `err` argument. Invoked with (callback).
+   * @param {Function} test - synchronous truth test to perform after each
+   * execution of `fn`. Invoked with the non-error callback results of `fn`.
+   * @param {Function} [callback] - A callback which is called after the test
+   * function has passed and repeated execution of `fn` has stopped. `callback`
+   * will be passed an error and any arguments passed to the final `fn`'s
+   * callback. Invoked with (err, [results]);
+   */
+  function doUntil(fn, test, callback) {
+      doWhilst(fn, function () {
+          return !test.apply(this, arguments);
+      }, callback);
+  }
+
+  function _withoutIndex(iteratee) {
+      return function (value, index, callback) {
+          return iteratee(value, callback);
+      };
+  }
+
+  /**
+   * The same as [`each`]{@link module:Collections.each} but runs a maximum of `limit` async operations at a time.
+   *
+   * @name eachLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.each]{@link module:Collections.each}
+   * @alias forEachLimit
+   * @category Collection
+   * @param {Array|Object} coll - A colleciton to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A function to apply to each item in `coll`. The
+   * iteratee is passed a `callback(err)` which must be called once it has
+   * completed. If no error has occurred, the `callback` should be run without
+   * arguments or with an explicit `null` argument. The array index is not passed
+   * to the iteratee. Invoked with (item, callback). If you need the index, use
+   * `eachOfLimit`.
+   * @param {Function} [callback] - A callback which is called when all
+   * `iteratee` functions have finished, or an error occurs. Invoked with (err).
+   */
+  function eachLimit(coll, limit, iteratee, callback) {
+    _eachOfLimit(limit)(coll, _withoutIndex(iteratee), callback);
+  }
+
+  /**
+   * Applies the function `iteratee` to each item in `coll`, in parallel.
+   * The `iteratee` is called with an item from the list, and a callback for when
+   * it has finished. If the `iteratee` passes an error to its `callback`, the
+   * main `callback` (for the `each` function) is immediately called with the
+   * error.
+   *
+   * Note, that since this function applies `iteratee` to each item in parallel,
+   * there is no guarantee that the iteratee functions will complete in order.
+   *
+   * @name each
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @alias forEach
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each item
+   * in `coll`. The iteratee is passed a `callback(err)` which must be called once
+   * it has completed. If no error has occurred, the `callback` should be run
+   * without arguments or with an explicit `null` argument. The array index is not
+   * passed to the iteratee. Invoked with (item, callback). If you need the index,
+   * use `eachOf`.
+   * @param {Function} [callback] - A callback which is called when all
+   * `iteratee` functions have finished, or an error occurs. Invoked with (err).
+   * @example
+   *
+   * // assuming openFiles is an array of file names and saveFile is a function
+   * // to save the modified contents of that file:
+   *
+   * async.each(openFiles, saveFile, function(err){
+   *   // if any of the saves produced an error, err would equal that error
+   * });
+   *
+   * // assuming openFiles is an array of file names
+   * async.each(openFiles, function(file, callback) {
+   *
+   *     // Perform operation on file here.
+   *     console.log('Processing file ' + file);
+   *
+   *     if( file.length > 32 ) {
+   *       console.log('This file name is too long');
+   *       callback('File name too long');
+   *     } else {
+   *       // Do work to process file here
+   *       console.log('File processed');
+   *       callback();
+   *     }
+   * }, function(err) {
+   *     // if any of the file processing produced an error, err would equal that error
+   *     if( err ) {
+   *       // One of the iterations produced an error.
+   *       // All processing will now stop.
+   *       console.log('A file failed to process');
+   *     } else {
+   *       console.log('All files have been processed successfully');
+   *     }
+   * });
+   */
+  var each = doLimit(eachLimit, Infinity);
+
+  /**
+   * The same as [`each`]{@link module:Collections.each} but runs only a single async operation at a time.
+   *
+   * @name eachSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.each]{@link module:Collections.each}
+   * @alias forEachSeries
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each
+   * item in `coll`. The iteratee is passed a `callback(err)` which must be called
+   * once it has completed. If no error has occurred, the `callback` should be run
+   * without arguments or with an explicit `null` argument. The array index is
+   * not passed to the iteratee. Invoked with (item, callback). If you need the
+   * index, use `eachOfSeries`.
+   * @param {Function} [callback] - A callback which is called when all
+   * `iteratee` functions have finished, or an error occurs. Invoked with (err).
+   */
+  var eachSeries = doLimit(eachLimit, 1);
+
+  /**
+   * Wrap an async function and ensure it calls its callback on a later tick of
+   * the event loop.  If the function already calls its callback on a next tick,
+   * no extra deferral is added. This is useful for preventing stack overflows
+   * (`RangeError: Maximum call stack size exceeded`) and generally keeping
+   * [Zalgo](http://blog.izs.me/post/59142742143/designing-apis-for-asynchrony)
+   * contained.
+   *
+   * @name ensureAsync
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {Function} fn - an async function, one that expects a node-style
+   * callback as its last argument.
+   * @returns {Function} Returns a wrapped function with the exact same call
+   * signature as the function passed in.
+   * @example
+   *
+   * function sometimesAsync(arg, callback) {
+   *     if (cache[arg]) {
+   *         return callback(null, cache[arg]); // this would be synchronous!!
+   *     } else {
+   *         doSomeIO(arg, callback); // this IO would be asynchronous
+   *     }
+   * }
+   *
+   * // this has a risk of stack overflows if many results are cached in a row
+   * async.mapSeries(args, sometimesAsync, done);
+   *
+   * // this will defer sometimesAsync's callback if necessary,
+   * // preventing stack overflows
+   * async.mapSeries(args, async.ensureAsync(sometimesAsync), done);
+   */
+  function ensureAsync(fn) {
+      return initialParams(function (args, callback) {
+          var sync = true;
+          args.push(function () {
+              var innerArgs = arguments;
+              if (sync) {
+                  setImmediate$1(function () {
+                      callback.apply(null, innerArgs);
+                  });
+              } else {
+                  callback.apply(null, innerArgs);
+              }
+          });
+          fn.apply(this, args);
+          sync = false;
+      });
+  }
+
+  function notId(v) {
+      return !v;
+  }
+
+  /**
+   * The same as [`every`]{@link module:Collections.every} but runs a maximum of `limit` async operations at a time.
+   *
+   * @name everyLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.every]{@link module:Collections.every}
+   * @alias allLimit
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A truth test to apply to each item in the
+   * collection in parallel. The iteratee is passed a `callback(err, truthValue)`
+   * which must be called with a  boolean argument once it has completed. Invoked
+   * with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Result will be either `true` or `false`
+   * depending on the values of the async tests. Invoked with (err, result).
+   */
+  var everyLimit = _createTester(eachOfLimit, notId, notId);
+
+  /**
+   * Returns `true` if every element in `coll` satisfies an async test. If any
+   * iteratee call returns `false`, the main `callback` is immediately called.
+   *
+   * @name every
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @alias all
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in the
+   * collection in parallel. The iteratee is passed a `callback(err, truthValue)`
+   * which must be called with a  boolean argument once it has completed. Invoked
+   * with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Result will be either `true` or `false`
+   * depending on the values of the async tests. Invoked with (err, result).
+   * @example
+   *
+   * async.every(['file1','file2','file3'], function(filePath, callback) {
+   *     fs.access(filePath, function(err) {
+   *         callback(null, !err)
+   *     });
+   * }, function(err, result) {
+   *     // if result is true then every file exists
+   * });
+   */
+  var every = doLimit(everyLimit, Infinity);
+
+  /**
+   * The same as [`every`]{@link module:Collections.every} but runs only a single async operation at a time.
+   *
+   * @name everySeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.every]{@link module:Collections.every}
+   * @alias allSeries
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in the
+   * collection in parallel. The iteratee is passed a `callback(err, truthValue)`
+   * which must be called with a  boolean argument once it has completed. Invoked
+   * with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Result will be either `true` or `false`
+   * depending on the values of the async tests. Invoked with (err, result).
+   */
+  var everySeries = doLimit(everyLimit, 1);
+
+  function _filter(eachfn, arr, iteratee, callback) {
+      var results = [];
+      eachfn(arr, function (x, index, callback) {
+          iteratee(x, function (err, v) {
+              if (err) {
+                  callback(err);
+              } else {
+                  if (v) {
+                      results.push({ index: index, value: x });
+                  }
+                  callback();
+              }
+          });
+      }, function (err) {
+          if (err) {
+              callback(err);
+          } else {
+              callback(null, arrayMap(results.sort(function (a, b) {
+                  return a.index - b.index;
+              }), baseProperty('value')));
           }
+      });
+  }
+
+  /**
+   * The same as [`filter`]{@link module:Collections.filter} but runs a maximum of `limit` async operations at a
+   * time.
+   *
+   * @name filterLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.filter]{@link module:Collections.filter}
+   * @alias selectLimit
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Invoked with (err, results).
+   */
+  var filterLimit = doParallelLimit(_filter);
+
+  /**
+   * Returns a new array of all the values in `coll` which pass an async truth
+   * test. This operation is performed in parallel, but the results array will be
+   * in the same order as the original.
+   *
+   * @name filter
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @alias select
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Invoked with (err, results).
+   * @example
+   *
+   * async.filter(['file1','file2','file3'], function(filePath, callback) {
+   *     fs.access(filePath, function(err) {
+   *         callback(null, !err)
+   *     });
+   * }, function(err, results) {
+   *     // results now equals an array of the existing files
+   * });
+   */
+  var filter = doLimit(filterLimit, Infinity);
+
+  /**
+   * The same as [`filter`]{@link module:Collections.filter} but runs only a single async operation at a time.
+   *
+   * @name filterSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.filter]{@link module:Collections.filter}
+   * @alias selectSeries
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Invoked with (err, results)
+   */
+  var filterSeries = doLimit(filterLimit, 1);
+
+  /**
+   * Calls the asynchronous function `fn` with a callback parameter that allows it
+   * to call itself again, in series, indefinitely.
+
+   * If an error is passed to the
+   * callback then `errback` is called with the error, and execution stops,
+   * otherwise it will never be called.
+   *
+   * @name forever
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Function} fn - a function to call repeatedly. Invoked with (next).
+   * @param {Function} [errback] - when `fn` passes an error to it's callback,
+   * this function will be called, and execution stops. Invoked with (err).
+   * @example
+   *
+   * async.forever(
+   *     function(next) {
+   *         // next is suitable for passing to things that need a callback(err [, whatever]);
+   *         // it will result in this function being called again.
+   *     },
+   *     function(err) {
+   *         // if next is called with a value in its first parameter, it will appear
+   *         // in here as 'err', and execution will stop.
+   *     }
+   * );
+   */
+  function forever(fn, errback) {
+      var done = onlyOnce(errback || noop);
+      var task = ensureAsync(fn);
+
+      function next(err) {
+          if (err) return done(err);
+          task(next);
       }
-      return false;
-    }
-
-    /** Used to compose bitmasks for comparison styles. */
-    var PARTIAL_COMPARE_FLAG$4 = 2;
-
-    /**
-     * A specialized version of `baseIsEqualDeep` for objects with support for
-     * partial deep comparisons.
-     *
-     * @private
-     * @param {Object} object The object to compare.
-     * @param {Object} other The other object to compare.
-     * @param {Function} equalFunc The function to determine equivalents of values.
-     * @param {Function} customizer The function to customize comparisons.
-     * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual`
-     *  for more details.
-     * @param {Object} stack Tracks traversed `object` and `other` objects.
-     * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
-     */
-    function equalObjects(object, other, equalFunc, customizer, bitmask, stack) {
-      var isPartial = bitmask & PARTIAL_COMPARE_FLAG$4,
-          objProps = keys(object),
-          objLength = objProps.length,
-          othProps = keys(other),
-          othLength = othProps.length;
-
-      if (objLength != othLength && !isPartial) {
-        return false;
-      }
-      var index = objLength;
-      while (index--) {
-        var key = objProps[index];
-        if (!(isPartial ? key in other : baseHas(other, key))) {
-          return false;
-        }
-      }
-      // Assume cyclic values are equal.
-      var stacked = stack.get(object);
-      if (stacked) {
-        return stacked == other;
-      }
-      var result = true;
-      stack.set(object, other);
-
-      var skipCtor = isPartial;
-      while (++index < objLength) {
-        key = objProps[index];
-        var objValue = object[key],
-            othValue = other[key];
-
-        if (customizer) {
-          var compared = isPartial
-            ? customizer(othValue, objValue, key, other, object, stack)
-            : customizer(objValue, othValue, key, object, other, stack);
-        }
-        // Recursively compare objects (susceptible to call stack limits).
-        if (!(compared === undefined
-              ? (objValue === othValue || equalFunc(objValue, othValue, customizer, bitmask, stack))
-              : compared
-            )) {
-          result = false;
-          break;
-        }
-        skipCtor || (skipCtor = key == 'constructor');
-      }
-      if (result && !skipCtor) {
-        var objCtor = object.constructor,
-            othCtor = other.constructor;
-
-        // Non `Object` object instances with different constructors are not equal.
-        if (objCtor != othCtor &&
-            ('constructor' in object && 'constructor' in other) &&
-            !(typeof objCtor == 'function' && objCtor instanceof objCtor &&
-              typeof othCtor == 'function' && othCtor instanceof othCtor)) {
-          result = false;
-        }
-      }
-      stack['delete'](object);
-      return result;
-    }
-
-    /* Built-in method references that are verified to be native. */
-    var DataView = getNative(root, 'DataView');
-
-    /* Built-in method references that are verified to be native. */
-    var Promise = getNative(root, 'Promise');
-
-    /* Built-in method references that are verified to be native. */
-    var Set = getNative(root, 'Set');
-
-    /* Built-in method references that are verified to be native. */
-    var WeakMap = getNative(root, 'WeakMap');
-
-    var mapTag$1 = '[object Map]';
-    var objectTag$1 = '[object Object]';
-    var promiseTag = '[object Promise]';
-    var setTag$1 = '[object Set]';
-    var weakMapTag = '[object WeakMap]';
-    var dataViewTag$1 = '[object DataView]';
-
-    /** Used for built-in method references. */
-    var objectProto$10 = Object.prototype;
-
-    /**
-     * Used to resolve the
-     * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
-     * of values.
-     */
-    var objectToString$4 = objectProto$10.toString;
-
-    /** Used to detect maps, sets, and weakmaps. */
-    var dataViewCtorString = toSource(DataView);
-    var mapCtorString = toSource(Map);
-    var promiseCtorString = toSource(Promise);
-    var setCtorString = toSource(Set);
-    var weakMapCtorString = toSource(WeakMap);
-    /**
-     * Gets the `toStringTag` of `value`.
-     *
-     * @private
-     * @param {*} value The value to query.
-     * @returns {string} Returns the `toStringTag`.
-     */
-    function getTag(value) {
-      return objectToString$4.call(value);
-    }
-
-    // Fallback for data views, maps, sets, and weak maps in IE 11,
-    // for data views in Edge, and promises in Node.js.
-    if ((DataView && getTag(new DataView(new ArrayBuffer(1))) != dataViewTag$1) ||
-        (Map && getTag(new Map) != mapTag$1) ||
-        (Promise && getTag(Promise.resolve()) != promiseTag) ||
-        (Set && getTag(new Set) != setTag$1) ||
-        (WeakMap && getTag(new WeakMap) != weakMapTag)) {
-      getTag = function(value) {
-        var result = objectToString$4.call(value),
-            Ctor = result == objectTag$1 ? value.constructor : undefined,
-            ctorString = Ctor ? toSource(Ctor) : undefined;
-
-        if (ctorString) {
-          switch (ctorString) {
-            case dataViewCtorString: return dataViewTag$1;
-            case mapCtorString: return mapTag$1;
-            case promiseCtorString: return promiseTag;
-            case setCtorString: return setTag$1;
-            case weakMapCtorString: return weakMapTag;
+      next();
+  }
+
+  /**
+   * Creates an iterator function which calls the next function in the `tasks`
+   * array, returning a continuation to call the next one after that. It's also
+   * possible to “peek” at the next iterator with `iterator.next()`.
+   *
+   * This function is used internally by the `async` module, but can be useful
+   * when you want to manually control the flow of functions in series.
+   *
+   * @name iterator
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Array} tasks - An array of functions to run.
+   * @returns The next function to run in the series.
+   * @example
+   *
+   * var iterator = async.iterator([
+   *     function() { sys.p('one'); },
+   *     function() { sys.p('two'); },
+   *     function() { sys.p('three'); }
+   * ]);
+   *
+   * node> var iterator2 = iterator();
+   * 'one'
+   * node> var iterator3 = iterator2();
+   * 'two'
+   * node> iterator3();
+   * 'three'
+   * node> var nextfn = iterator2.next();
+   * node> nextfn();
+   * 'three'
+   */
+  function iterator$1 (tasks) {
+      function makeCallback(index) {
+          function fn() {
+              if (tasks.length) {
+                  tasks[index].apply(null, arguments);
+              }
+              return fn.next();
           }
-        }
-        return result;
-      };
-    }
-
-    var getTag$1 = getTag;
-
-    var argsTag$2 = '[object Arguments]';
-    var arrayTag$1 = '[object Array]';
-    var boolTag$1 = '[object Boolean]';
-    var dateTag$1 = '[object Date]';
-    var errorTag$1 = '[object Error]';
-    var funcTag$1 = '[object Function]';
-    var mapTag$2 = '[object Map]';
-    var numberTag$1 = '[object Number]';
-    var objectTag$2 = '[object Object]';
-    var regexpTag$1 = '[object RegExp]';
-    var setTag$2 = '[object Set]';
-    var stringTag$2 = '[object String]';
-    var weakMapTag$1 = '[object WeakMap]';
-    var arrayBufferTag$1 = '[object ArrayBuffer]';
-    var dataViewTag$2 = '[object DataView]';
-    var float32Tag = '[object Float32Array]';
-    var float64Tag = '[object Float64Array]';
-    var int8Tag = '[object Int8Array]';
-    var int16Tag = '[object Int16Array]';
-    var int32Tag = '[object Int32Array]';
-    var uint8Tag = '[object Uint8Array]';
-    var uint8ClampedTag = '[object Uint8ClampedArray]';
-    var uint16Tag = '[object Uint16Array]';
-    var uint32Tag = '[object Uint32Array]';
-    /** Used to identify `toStringTag` values of typed arrays. */
-    var typedArrayTags = {};
-    typedArrayTags[float32Tag] = typedArrayTags[float64Tag] =
-    typedArrayTags[int8Tag] = typedArrayTags[int16Tag] =
-    typedArrayTags[int32Tag] = typedArrayTags[uint8Tag] =
-    typedArrayTags[uint8ClampedTag] = typedArrayTags[uint16Tag] =
-    typedArrayTags[uint32Tag] = true;
-    typedArrayTags[argsTag$2] = typedArrayTags[arrayTag$1] =
-    typedArrayTags[arrayBufferTag$1] = typedArrayTags[boolTag$1] =
-    typedArrayTags[dataViewTag$2] = typedArrayTags[dateTag$1] =
-    typedArrayTags[errorTag$1] = typedArrayTags[funcTag$1] =
-    typedArrayTags[mapTag$2] = typedArrayTags[numberTag$1] =
-    typedArrayTags[objectTag$2] = typedArrayTags[regexpTag$1] =
-    typedArrayTags[setTag$2] = typedArrayTags[stringTag$2] =
-    typedArrayTags[weakMapTag$1] = false;
-
-    /** Used for built-in method references. */
-    var objectProto$11 = Object.prototype;
-
-    /**
-     * Used to resolve the
-     * [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
-     * of values.
-     */
-    var objectToString$5 = objectProto$11.toString;
-
-    /**
-     * Checks if `value` is classified as a typed array.
-     *
-     * @static
-     * @memberOf _
-     * @since 3.0.0
-     * @category Lang
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` is correctly classified,
-     *  else `false`.
-     * @example
-     *
-     * _.isTypedArray(new Uint8Array);
-     * // => true
-     *
-     * _.isTypedArray([]);
-     * // => false
-     */
-    function isTypedArray(value) {
-      return isObjectLike(value) &&
-        isLength(value.length) && !!typedArrayTags[objectToString$5.call(value)];
-    }
-
-    /** Used to compose bitmasks for comparison styles. */
-    var PARTIAL_COMPARE_FLAG$1 = 2;
-
-    /** `Object#toString` result references. */
-    var argsTag$1 = '[object Arguments]';
-    var arrayTag = '[object Array]';
-    var objectTag = '[object Object]';
-    /** Used for built-in method references. */
-    var objectProto$9 = Object.prototype;
-
-    /** Used to check objects for own properties. */
-    var hasOwnProperty$5 = objectProto$9.hasOwnProperty;
-
-    /**
-     * A specialized version of `baseIsEqual` for arrays and objects which performs
-     * deep comparisons and tracks traversed objects enabling objects with circular
-     * references to be compared.
-     *
-     * @private
-     * @param {Object} object The object to compare.
-     * @param {Object} other The other object to compare.
-     * @param {Function} equalFunc The function to determine equivalents of values.
-     * @param {Function} [customizer] The function to customize comparisons.
-     * @param {number} [bitmask] The bitmask of comparison flags. See `baseIsEqual`
-     *  for more details.
-     * @param {Object} [stack] Tracks traversed `object` and `other` objects.
-     * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
-     */
-    function baseIsEqualDeep(object, other, equalFunc, customizer, bitmask, stack) {
-      var objIsArr = isArray(object),
-          othIsArr = isArray(other),
-          objTag = arrayTag,
-          othTag = arrayTag;
-
-      if (!objIsArr) {
-        objTag = getTag$1(object);
-        objTag = objTag == argsTag$1 ? objectTag : objTag;
-      }
-      if (!othIsArr) {
-        othTag = getTag$1(other);
-        othTag = othTag == argsTag$1 ? objectTag : othTag;
-      }
-      var objIsObj = objTag == objectTag && !isHostObject(object),
-          othIsObj = othTag == objectTag && !isHostObject(other),
-          isSameTag = objTag == othTag;
-
-      if (isSameTag && !objIsObj) {
-        stack || (stack = new Stack);
-        return (objIsArr || isTypedArray(object))
-          ? equalArrays(object, other, equalFunc, customizer, bitmask, stack)
-          : equalByTag(object, other, objTag, equalFunc, customizer, bitmask, stack);
-      }
-      if (!(bitmask & PARTIAL_COMPARE_FLAG$1)) {
-        var objIsWrapped = objIsObj && hasOwnProperty$5.call(object, '__wrapped__'),
-            othIsWrapped = othIsObj && hasOwnProperty$5.call(other, '__wrapped__');
-
-        if (objIsWrapped || othIsWrapped) {
-          var objUnwrapped = objIsWrapped ? object.value() : object,
-              othUnwrapped = othIsWrapped ? other.value() : other;
-
-          stack || (stack = new Stack);
-          return equalFunc(objUnwrapped, othUnwrapped, customizer, bitmask, stack);
-        }
+          fn.next = function () {
+              return index < tasks.length - 1 ? makeCallback(index + 1) : null;
+          };
+          return fn;
       }
-      if (!isSameTag) {
-        return false;
-      }
-      stack || (stack = new Stack);
-      return equalObjects(object, other, equalFunc, customizer, bitmask, stack);
-    }
-
-    /**
-     * The base implementation of `_.isEqual` which supports partial comparisons
-     * and tracks traversed objects.
-     *
-     * @private
-     * @param {*} value The value to compare.
-     * @param {*} other The other value to compare.
-     * @param {Function} [customizer] The function to customize comparisons.
-     * @param {boolean} [bitmask] The bitmask of comparison flags.
-     *  The bitmask may be composed of the following flags:
-     *     1 - Unordered comparison
-     *     2 - Partial comparison
-     * @param {Object} [stack] Tracks traversed `value` and `other` objects.
-     * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
-     */
-    function baseIsEqual(value, other, customizer, bitmask, stack) {
-      if (value === other) {
-        return true;
-      }
-      if (value == null || other == null || (!isObject(value) && !isObjectLike(other))) {
-        return value !== value && other !== other;
-      }
-      return baseIsEqualDeep(value, other, baseIsEqual, customizer, bitmask, stack);
-    }
-
-    var UNORDERED_COMPARE_FLAG = 1;
-    var PARTIAL_COMPARE_FLAG = 2;
-    /**
-     * The base implementation of `_.isMatch` without support for iteratee shorthands.
-     *
-     * @private
-     * @param {Object} object The object to inspect.
-     * @param {Object} source The object of property values to match.
-     * @param {Array} matchData The property names, values, and compare flags to match.
-     * @param {Function} [customizer] The function to customize comparisons.
-     * @returns {boolean} Returns `true` if `object` is a match, else `false`.
-     */
-    function baseIsMatch(object, source, matchData, customizer) {
-      var index = matchData.length,
-          length = index,
-          noCustomizer = !customizer;
-
-      if (object == null) {
-        return !length;
-      }
-      object = Object(object);
-      while (index--) {
-        var data = matchData[index];
-        if ((noCustomizer && data[2])
-              ? data[1] !== object[data[0]]
-              : !(data[0] in object)
-            ) {
-          return false;
-        }
-      }
-      while (++index < length) {
-        data = matchData[index];
-        var key = data[0],
-            objValue = object[key],
-            srcValue = data[1];
-
-        if (noCustomizer && data[2]) {
-          if (objValue === undefined && !(key in object)) {
-            return false;
+      return makeCallback(0);
+  }
+
+  /**
+   * Logs the result of an `async` function to the `console`. Only works in
+   * Node.js or in browsers that support `console.log` and `console.error` (such
+   * as FF and Chrome). If multiple arguments are returned from the async
+   * function, `console.log` is called on each argument in order.
+   *
+   * @name log
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {Function} function - The function you want to eventually apply all
+   * arguments to.
+   * @param {...*} arguments... - Any number of arguments to apply to the function.
+   * @example
+   *
+   * // in a module
+   * var hello = function(name, callback) {
+   *     setTimeout(function() {
+   *         callback(null, 'hello ' + name);
+   *     }, 1000);
+   * };
+   *
+   * // in the node repl
+   * node> async.log(hello, 'world');
+   * 'hello world'
+   */
+  var log = consoleFunc('log');
+
+  /**
+   * The same as [`mapValues`]{@link module:Collections.mapValues} but runs a maximum of `limit` async operations at a
+   * time.
+   *
+   * @name mapValuesLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.mapValues]{@link module:Collections.mapValues}
+   * @category Collection
+   * @param {Object} obj - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A function to apply to each value in `obj`.
+   * The iteratee is passed a `callback(err, transformed)` which must be called
+   * once it has completed with an error (which can be `null`) and a
+   * transformed value. Invoked with (value, key, callback).
+   * @param {Function} [callback] - A callback which is called when all `iteratee`
+   * functions have finished, or an error occurs. Result is an object of the
+   * transformed values from the `obj`. Invoked with (err, result).
+   */
+  function mapValuesLimit(obj, limit, iteratee, callback) {
+      var newObj = {};
+      eachOfLimit(obj, limit, function (val, key, next) {
+          iteratee(val, key, function (err, result) {
+              if (err) return next(err);
+              newObj[key] = result;
+              next();
+          });
+      }, function (err) {
+          callback(err, newObj);
+      });
+  }
+
+  /**
+   * A relative of [`map`]{@link module:Collections.map}, designed for use with objects.
+   *
+   * Produces a new Object by mapping each value of `obj` through the `iteratee`
+   * function. The `iteratee` is called each `value` and `key` from `obj` and a
+   * callback for when it has finished processing. Each of these callbacks takes
+   * two arguments: an `error`, and the transformed item from `obj`. If `iteratee`
+   * passes an error to its callback, the main `callback` (for the `mapValues`
+   * function) is immediately called with the error.
+   *
+   * Note, the order of the keys in the result is not guaranteed.  The keys will
+   * be roughly in the order they complete, (but this is very engine-specific)
+   *
+   * @name mapValues
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @category Collection
+   * @param {Object} obj - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each value and key in
+   * `coll`. The iteratee is passed a `callback(err, transformed)` which must be
+   * called once it has completed with an error (which can be `null`) and a
+   * transformed value. Invoked with (value, key, callback).
+   * @param {Function} [callback] - A callback which is called when all `iteratee`
+   * functions have finished, or an error occurs. Results is an array of the
+   * transformed items from the `obj`. Invoked with (err, result).
+   * @example
+   *
+   * async.mapValues({
+   *     f1: 'file1',
+   *     f2: 'file2',
+   *     f3: 'file3'
+   * }, fs.stat, function(err, result) {
+   *     // results is now a map of stats for each file, e.g.
+   *     // {
+   *     //     f1: [stats for file1],
+   *     //     f2: [stats for file2],
+   *     //     f3: [stats for file3]
+   *     // }
+   * });
+   */
+
+  var mapValues = doLimit(mapValuesLimit, Infinity);
+
+  /**
+   * The same as [`mapValues`]{@link module:Collections.mapValues} but runs only a single async operation at a time.
+   *
+   * @name mapValuesSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.mapValues]{@link module:Collections.mapValues}
+   * @category Collection
+   * @param {Object} obj - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each value in `obj`.
+   * The iteratee is passed a `callback(err, transformed)` which must be called
+   * once it has completed with an error (which can be `null`) and a
+   * transformed value. Invoked with (value, key, callback).
+   * @param {Function} [callback] - A callback which is called when all `iteratee`
+   * functions have finished, or an error occurs. Result is an object of the
+   * transformed values from the `obj`. Invoked with (err, result).
+   */
+  var mapValuesSeries = doLimit(mapValuesLimit, 1);
+
+  function has(obj, key) {
+      return key in obj;
+  }
+
+  /**
+   * Caches the results of an `async` function. When creating a hash to store
+   * function results against, the callback is omitted from the hash and an
+   * optional hash function can be used.
+   *
+   * If no hash function is specified, the first argument is used as a hash key,
+   * which may work reasonably if it is a string or a data type that converts to a
+   * distinct string. Note that objects and arrays will not behave reasonably.
+   * Neither will cases where the other arguments are significant. In such cases,
+   * specify your own hash function.
+   *
+   * The cache of results is exposed as the `memo` property of the function
+   * returned by `memoize`.
+   *
+   * @name memoize
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {Function} fn - The function to proxy and cache results from.
+   * @param {Function} hasher - An optional function for generating a custom hash
+   * for storing results. It has all the arguments applied to it apart from the
+   * callback, and must be synchronous.
+   * @returns {Function} a memoized version of `fn`
+   * @example
+   *
+   * var slow_fn = function(name, callback) {
+   *     // do something
+   *     callback(null, result);
+   * };
+   * var fn = async.memoize(slow_fn);
+   *
+   * // fn can now be used as if it were slow_fn
+   * fn('some name', function() {
+   *     // callback
+   * });
+   */
+  function memoize(fn, hasher) {
+      var memo = Object.create(null);
+      var queues = Object.create(null);
+      hasher = hasher || identity;
+      var memoized = initialParams(function memoized(args, callback) {
+          var key = hasher.apply(null, args);
+          if (has(memo, key)) {
+              setImmediate$1(function () {
+                  callback.apply(null, memo[key]);
+              });
+          } else if (has(queues, key)) {
+              queues[key].push(callback);
+          } else {
+              queues[key] = [callback];
+              fn.apply(null, args.concat([rest(function (args) {
+                  memo[key] = args;
+                  var q = queues[key];
+                  delete queues[key];
+                  for (var i = 0, l = q.length; i < l; i++) {
+                      q[i].apply(null, args);
+                  }
+              })]));
           }
-        } else {
-          var stack = new Stack;
-          if (customizer) {
-            var result = customizer(objValue, srcValue, key, object, source, stack);
+      });
+      memoized.memo = memo;
+      memoized.unmemoized = fn;
+      return memoized;
+  }
+
+  /**
+   * Calls `callback` on a later loop around the event loop. In Node.js this just
+   * calls `setImmediate`.  In the browser it will use `setImmediate` if
+   * available, otherwise `setTimeout(callback, 0)`, which means other higher
+   * priority events may precede the execution of `callback`.
+   *
+   * This is used internally for browser-compatibility purposes.
+   *
+   * @name nextTick
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @alias setImmediate
+   * @category Util
+   * @param {Function} callback - The function to call on a later loop around
+   * the event loop. Invoked with (args...).
+   * @param {...*} args... - any number of additional arguments to pass to the
+   * callback on the next tick.
+   * @example
+   *
+   * var call_order = [];
+   * async.nextTick(function() {
+   *     call_order.push('two');
+   *     // call_order now equals ['one','two']
+   * });
+   * call_order.push('one');
+   *
+   * async.setImmediate(function (a, b, c) {
+   *     // a, b, and c equal 1, 2, and 3
+   * }, 1, 2, 3);
+   */
+  var _defer$1;
+
+  if (hasNextTick) {
+      _defer$1 = process.nextTick;
+  } else if (hasSetImmediate) {
+      _defer$1 = setImmediate;
+  } else {
+      _defer$1 = fallback;
+  }
+
+  var nextTick = wrap(_defer$1);
+
+  function _parallel(eachfn, tasks, callback) {
+      callback = callback || noop;
+      var results = isArrayLike(tasks) ? [] : {};
+
+      eachfn(tasks, function (task, key, callback) {
+          task(rest(function (err, args) {
+              if (args.length <= 1) {
+                  args = args[0];
+              }
+              results[key] = args;
+              callback(err);
+          }));
+      }, function (err) {
+          callback(err, results);
+      });
+  }
+
+  /**
+   * The same as [`parallel`]{@link module:ControlFlow.parallel} but runs a maximum of `limit` async operations at a
+   * time.
+   *
+   * @name parallelLimit
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.parallel]{@link module:ControlFlow.parallel}
+   * @category Control Flow
+   * @param {Array|Collection} tasks - A collection containing functions to run.
+   * Each function is passed a `callback(err, result)` which it must call on
+   * completion with an error `err` (which can be `null`) and an optional `result`
+   * value.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} [callback] - An optional callback to run once all the
+   * functions have completed successfully. This function gets a results array
+   * (or object) containing all the result arguments passed to the task callbacks.
+   * Invoked with (err, results).
+   */
+  function parallelLimit(tasks, limit, callback) {
+    _parallel(_eachOfLimit(limit), tasks, callback);
+  }
+
+  /**
+   * Run the `tasks` collection of functions in parallel, without waiting until
+   * the previous function has completed. If any of the functions pass an error to
+   * its callback, the main `callback` is immediately called with the value of the
+   * error. Once the `tasks` have completed, the results are passed to the final
+   * `callback` as an array.
+   *
+   * **Note:** `parallel` is about kicking-off I/O tasks in parallel, not about
+   * parallel execution of code.  If your tasks do not use any timers or perform
+   * any I/O, they will actually be executed in series.  Any synchronous setup
+   * sections for each task will happen one after the other.  JavaScript remains
+   * single-threaded.
+   *
+   * It is also possible to use an object instead of an array. Each property will
+   * be run as a function and the results will be passed to the final `callback`
+   * as an object instead of an array. This can be a more readable way of handling
+   * results from {@link async.parallel}.
+   *
+   * @name parallel
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Array|Object} tasks - A collection containing functions to run.
+   * Each function is passed a `callback(err, result)` which it must call on
+   * completion with an error `err` (which can be `null`) and an optional `result`
+   * value.
+   * @param {Function} [callback] - An optional callback to run once all the
+   * functions have completed successfully. This function gets a results array
+   * (or object) containing all the result arguments passed to the task callbacks.
+   * Invoked with (err, results).
+   * @example
+   * async.parallel([
+   *     function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'one');
+   *         }, 200);
+   *     },
+   *     function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'two');
+   *         }, 100);
+   *     }
+   * ],
+   * // optional callback
+   * function(err, results) {
+   *     // the results array will equal ['one','two'] even though
+   *     // the second function had a shorter timeout.
+   * });
+   *
+   * // an example using an object instead of an array
+   * async.parallel({
+   *     one: function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 1);
+   *         }, 200);
+   *     },
+   *     two: function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 2);
+   *         }, 100);
+   *     }
+   * }, function(err, results) {
+   *     // results is now equals to: {one: 1, two: 2}
+   * });
+   */
+  var parallel = doLimit(parallelLimit, Infinity);
+
+  /**
+   * A queue of tasks for the worker function to complete.
+   * @typedef {Object} QueueObject
+   * @memberOf module:ControlFlow
+   * @property {Function} length - a function returning the number of items
+   * waiting to be processed. Invoke with `queue.length()`.
+   * @property {Function} started - a function returning whether or not any
+   * items have been pushed and processed by the queue. Invoke with `queue.started()`.
+   * @property {Function} running - a function returning the number of items
+   * currently being processed. Invoke with `queue.running()`.
+   * @property {Function} workersList - a function returning the array of items
+   * currently being processed. Invoke with `queue.workersList()`.
+   * @property {Function} idle - a function returning false if there are items
+   * waiting or being processed, or true if not. Invoke with `queue.idle()`.
+   * @property {number} concurrency - an integer for determining how many `worker`
+   * functions should be run in parallel. This property can be changed after a
+   * `queue` is created to alter the concurrency on-the-fly.
+   * @property {Function} push - add a new task to the `queue`. Calls `callback`
+   * once the `worker` has finished processing the task. Instead of a single task,
+   * a `tasks` array can be submitted. The respective callback is used for every
+   * task in the list. Invoke with `queue.push(task, [callback])`,
+   * @property {Function} unshift - add a new task to the front of the `queue`.
+   * Invoke with `queue.unshift(task, [callback])`.
+   * @property {Function} saturated - a callback that is called when the number of
+   * running workers hits the `concurrency` limit, and further tasks will be
+   * queued.
+   * @property {Function} unsaturated - a callback that is called when the number
+   * of running workers is less than the `concurrency` & `buffer` limits, and
+   * further tasks will not be queued.
+   * @property {number} buffer - A minimum threshold buffer in order to say that
+   * the `queue` is `unsaturated`.
+   * @property {Function} empty - a callback that is called when the last item
+   * from the `queue` is given to a `worker`.
+   * @property {Function} drain - a callback that is called when the last item
+   * from the `queue` has returned from the `worker`.
+   * @property {Function} error - a callback that is called when a task errors.
+   * Has the signature `function(error, task)`.
+   * @property {boolean} paused - a boolean for determining whether the queue is
+   * in a paused state.
+   * @property {Function} pause - a function that pauses the processing of tasks
+   * until `resume()` is called. Invoke with `queue.pause()`.
+   * @property {Function} resume - a function that resumes the processing of
+   * queued tasks when the queue is paused. Invoke with `queue.length()`.
+   * @property {Function} kill - a function that removes the `drain` callback and
+   * empties remaining tasks from the queue forcing it to go idle. Invoke with `queue.kill()`.
+   */
+
+  /**
+   * Creates a `queue` object with the specified `concurrency`. Tasks added to the
+   * `queue` are processed in parallel (up to the `concurrency` limit). If all
+   * `worker`s are in progress, the task is queued until one becomes available.
+   * Once a `worker` completes a `task`, that `task`'s callback is called.
+   *
+   * @name queue
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Function} worker - An asynchronous function for processing a queued
+   * task, which must call its `callback(err)` argument when finished, with an
+   * optional `error` as an argument.  If you want to handle errors from an
+   * individual task, pass a callback to `q.push()`. Invoked with
+   * (task, callback).
+   * @param {number} [concurrency=1] - An `integer` for determining how many
+   * `worker` functions should be run in parallel.  If omitted, the concurrency
+   * defaults to `1`.  If the concurrency is `0`, an error is thrown.
+   * @returns {module:ControlFlow.QueueObject} A queue object to manage the tasks. Callbacks can
+   * attached as certain properties to listen for specific events during the
+   * lifecycle of the queue.
+   * @example
+   *
+   * // create a queue object with concurrency 2
+   * var q = async.queue(function(task, callback) {
+   *     console.log('hello ' + task.name);
+   *     callback();
+   * }, 2);
+   *
+   * // assign a callback
+   * q.drain = function() {
+   *     console.log('all items have been processed');
+   * };
+   *
+   * // add some items to the queue
+   * q.push({name: 'foo'}, function(err) {
+   *     console.log('finished processing foo');
+   * });
+   * q.push({name: 'bar'}, function (err) {
+   *     console.log('finished processing bar');
+   * });
+   *
+   * // add some items to the queue (batch-wise)
+   * q.push([{name: 'baz'},{name: 'bay'},{name: 'bax'}], function(err) {
+   *     console.log('finished processing item');
+   * });
+   *
+   * // add some items to the front of the queue
+   * q.unshift({name: 'bar'}, function (err) {
+   *     console.log('finished processing bar');
+   * });
+   */
+  function queue$1 (worker, concurrency) {
+    return queue(function (items, cb) {
+      worker(items[0], cb);
+    }, concurrency, 1);
+  }
+
+  /**
+   * The same as [async.queue]{@link module:ControlFlow.queue} only tasks are assigned a priority and
+   * completed in ascending priority order.
+   *
+   * @name priorityQueue
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.queue]{@link module:ControlFlow.queue}
+   * @category Control Flow
+   * @param {Function} worker - An asynchronous function for processing a queued
+   * task, which must call its `callback(err)` argument when finished, with an
+   * optional `error` as an argument.  If you want to handle errors from an
+   * individual task, pass a callback to `q.push()`. Invoked with
+   * (task, callback).
+   * @param {number} concurrency - An `integer` for determining how many `worker`
+   * functions should be run in parallel.  If omitted, the concurrency defaults to
+   * `1`.  If the concurrency is `0`, an error is thrown.
+   * @returns {module:ControlFlow.QueueObject} A priorityQueue object to manage the tasks. There are two
+   * differences between `queue` and `priorityQueue` objects:
+   * * `push(task, priority, [callback])` - `priority` should be a number. If an
+   *   array of `tasks` is given, all tasks will be assigned the same priority.
+   * * The `unshift` method was removed.
+   */
+  function priorityQueue (worker, concurrency) {
+      // Start with a normal queue
+      var q = queue$1(worker, concurrency);
+
+      // Override push to accept second parameter representing priority
+      q.push = function (data, priority, callback) {
+          if (callback == null) callback = noop;
+          if (typeof callback !== 'function') {
+              throw new Error('task callback must be a function');
           }
-          if (!(result === undefined
-                ? baseIsEqual(srcValue, objValue, customizer, UNORDERED_COMPARE_FLAG | PARTIAL_COMPARE_FLAG, stack)
-                : result
-              )) {
-            return false;
+          q.started = true;
+          if (!isArray(data)) {
+              data = [data];
+          }
+          if (data.length === 0) {
+              // call drain immediately if there are no tasks
+              return setImmediate$1(function () {
+                  q.drain();
+              });
           }
-        }
-      }
-      return true;
-    }
-
-    /**
-     * Checks if `value` is suitable for strict equality comparisons, i.e. `===`.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @returns {boolean} Returns `true` if `value` if suitable for strict
-     *  equality comparisons, else `false`.
-     */
-    function isStrictComparable(value) {
-      return value === value && !isObject(value);
-    }
-
-    /**
-     * Gets the property names, values, and compare flags of `object`.
-     *
-     * @private
-     * @param {Object} object The object to query.
-     * @returns {Array} Returns the match data of `object`.
-     */
-    function getMatchData(object) {
-      var result = keys(object),
-          length = result.length;
-
-      while (length--) {
-        var key = result[length],
-            value = object[key];
-
-        result[length] = [key, value, isStrictComparable(value)];
-      }
-      return result;
-    }
 
-    /**
-     * A specialized version of `matchesProperty` for source values suitable
-     * for strict equality comparisons, i.e. `===`.
-     *
-     * @private
-     * @param {string} key The key of the property to get.
-     * @param {*} srcValue The value to match.
-     * @returns {Function} Returns the new spec function.
-     */
-    function matchesStrictComparable(key, srcValue) {
-      return function(object) {
-        if (object == null) {
-          return false;
-        }
-        return object[key] === srcValue &&
-          (srcValue !== undefined || (key in Object(object)));
-      };
-    }
+          var nextNode = q._tasks.head;
+          while (nextNode && priority >= nextNode.priority) {
+              nextNode = nextNode.next;
+          }
 
-    /**
-     * The base implementation of `_.matches` which doesn't clone `source`.
-     *
-     * @private
-     * @param {Object} source The object of property values to match.
-     * @returns {Function} Returns the new spec function.
-     */
-    function baseMatches(source) {
-      var matchData = getMatchData(source);
-      if (matchData.length == 1 && matchData[0][2]) {
-        return matchesStrictComparable(matchData[0][0], matchData[0][1]);
-      }
-      return function(object) {
-        return object === source || baseIsMatch(object, source, matchData);
+          arrayEach(data, function (task) {
+              var item = {
+                  data: task,
+                  priority: priority,
+                  callback: callback
+              };
+
+              if (nextNode) {
+                  q._tasks.insertBefore(nextNode, item);
+              } else {
+                  q._tasks.push(item);
+              }
+          });
+          setImmediate$1(q.process);
       };
-    }
 
-    /** Used as the `TypeError` message for "Functions" methods. */
-    var FUNC_ERROR_TEXT$1 = 'Expected a function';
-
-    /**
-     * Creates a function that memoizes the result of `func`. If `resolver` is
-     * provided, it determines the cache key for storing the result based on the
-     * arguments provided to the memoized function. By default, the first argument
-     * provided to the memoized function is used as the map cache key. The `func`
-     * is invoked with the `this` binding of the memoized function.
-     *
-     * **Note:** The cache is exposed as the `cache` property on the memoized
-     * function. Its creation may be customized by replacing the `_.memoize.Cache`
-     * constructor with one whose instances implement the
-     * [`Map`](http://ecma-international.org/ecma-262/6.0/#sec-properties-of-the-map-prototype-object)
-     * method interface of `delete`, `get`, `has`, and `set`.
-     *
-     * @static
-     * @memberOf _
-     * @since 0.1.0
-     * @category Function
-     * @param {Function} func The function to have its output memoized.
-     * @param {Function} [resolver] The function to resolve the cache key.
-     * @returns {Function} Returns the new memoized function.
-     * @example
-     *
-     * var object = { 'a': 1, 'b': 2 };
-     * var other = { 'c': 3, 'd': 4 };
-     *
-     * var values = _.memoize(_.values);
-     * values(object);
-     * // => [1, 2]
-     *
-     * values(other);
-     * // => [3, 4]
-     *
-     * object.a = 2;
-     * values(object);
-     * // => [1, 2]
-     *
-     * // Modify the result cache.
-     * values.cache.set(object, ['a', 'b']);
-     * values(object);
-     * // => ['a', 'b']
-     *
-     * // Replace `_.memoize.Cache`.
-     * _.memoize.Cache = WeakMap;
-     */
-    function memoize(func, resolver) {
-      if (typeof func != 'function' || (resolver && typeof resolver != 'function')) {
-        throw new TypeError(FUNC_ERROR_TEXT$1);
-      }
-      var memoized = function() {
-        var args = arguments,
-            key = resolver ? resolver.apply(this, args) : args[0],
-            cache = memoized.cache;
-
-        if (cache.has(key)) {
-          return cache.get(key);
-        }
-        var result = func.apply(this, args);
-        memoized.cache = cache.set(key, result);
-        return result;
-      };
-      memoized.cache = new (memoize.Cache || MapCache);
-      return memoized;
-    }
-
-    // Assign cache to `_.memoize`.
-    memoize.Cache = MapCache;
-
-    /** Used as references for various `Number` constants. */
-    var INFINITY$1 = 1 / 0;
-
-    /** Used to convert symbols to primitives and strings. */
-    var symbolProto$1 = Symbol$1 ? Symbol$1.prototype : undefined;
-    var symbolToString = symbolProto$1 ? symbolProto$1.toString : undefined;
-    /**
-     * The base implementation of `_.toString` which doesn't convert nullish
-     * values to empty strings.
-     *
-     * @private
-     * @param {*} value The value to process.
-     * @returns {string} Returns the string.
-     */
-    function baseToString(value) {
-      // Exit early for strings to avoid a performance hit in some environments.
-      if (typeof value == 'string') {
-        return value;
-      }
-      if (isSymbol(value)) {
-        return symbolToString ? symbolToString.call(value) : '';
-      }
-      var result = (value + '');
-      return (result == '0' && (1 / value) == -INFINITY$1) ? '-0' : result;
-    }
-
-    /**
-     * Converts `value` to a string. An empty string is returned for `null`
-     * and `undefined` values. The sign of `-0` is preserved.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Lang
-     * @param {*} value The value to process.
-     * @returns {string} Returns the string.
-     * @example
-     *
-     * _.toString(null);
-     * // => ''
-     *
-     * _.toString(-0);
-     * // => '-0'
-     *
-     * _.toString([1, 2, 3]);
-     * // => '1,2,3'
-     */
-    function toString(value) {
-      return value == null ? '' : baseToString(value);
-    }
-
-    /** Used to match property names within property paths. */
-    var rePropName = /[^.[\]]+|\[(?:(-?\d+(?:\.\d+)?)|(["'])((?:(?!\2)[^\\]|\\.)*?)\2)\]|(?=(\.|\[\])(?:\4|$))/g;
-
-    /** Used to match backslashes in property paths. */
-    var reEscapeChar = /\\(\\)?/g;
-
-    /**
-     * Converts `string` to a property path array.
-     *
-     * @private
-     * @param {string} string The string to convert.
-     * @returns {Array} Returns the property path array.
-     */
-    var stringToPath = memoize(function(string) {
-      var result = [];
-      toString(string).replace(rePropName, function(match, number, quote, string) {
-        result.push(quote ? string.replace(reEscapeChar, '$1') : (number || match));
+      // Remove unshift function
+      delete q.unshift;
+
+      return q;
+  }
+
+  /**
+   * Runs the `tasks` array of functions in parallel, without waiting until the
+   * previous function has completed. Once any the `tasks` completed or pass an
+   * error to its callback, the main `callback` is immediately called. It's
+   * equivalent to `Promise.race()`.
+   *
+   * @name race
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Array} tasks - An array containing functions to run. Each function
+   * is passed a `callback(err, result)` which it must call on completion with an
+   * error `err` (which can be `null`) and an optional `result` value.
+   * @param {Function} callback - A callback to run once any of the functions have
+   * completed. This function gets an error or result from the first function that
+   * completed. Invoked with (err, result).
+   * @returns undefined
+   * @example
+   *
+   * async.race([
+   *     function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'one');
+   *         }, 200);
+   *     },
+   *     function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'two');
+   *         }, 100);
+   *     }
+   * ],
+   * // main callback
+   * function(err, result) {
+   *     // the result will be equal to 'two' as it finishes earlier
+   * });
+   */
+  function race(tasks, callback) {
+      callback = once(callback || noop);
+      if (!isArray(tasks)) return callback(new TypeError('First argument to race must be an array of functions'));
+      if (!tasks.length) return callback();
+      arrayEach(tasks, function (task) {
+          task(callback);
       });
-      return result;
-    });
-
-    /**
-     * Casts `value` to a path array if it's not one.
-     *
-     * @private
-     * @param {*} value The value to inspect.
-     * @returns {Array} Returns the cast property path array.
-     */
-    function castPath(value) {
-      return isArray(value) ? value : stringToPath(value);
-    }
-
-    var reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\\]|\\.)*?\1)\]/;
-    var reIsPlainProp = /^\w*$/;
-    /**
-     * Checks if `value` is a property name and not a property path.
-     *
-     * @private
-     * @param {*} value The value to check.
-     * @param {Object} [object] The object to query keys on.
-     * @returns {boolean} Returns `true` if `value` is a property name, else `false`.
-     */
-    function isKey(value, object) {
-      if (isArray(value)) {
-        return false;
-      }
-      var type = typeof value;
-      if (type == 'number' || type == 'symbol' || type == 'boolean' ||
-          value == null || isSymbol(value)) {
-        return true;
-      }
-      return reIsPlainProp.test(value) || !reIsDeepProp.test(value) ||
-        (object != null && value in Object(object));
-    }
-
-    /** Used as references for various `Number` constants. */
-    var INFINITY$2 = 1 / 0;
-
-    /**
-     * Converts `value` to a string key if it's not a string or symbol.
-     *
-     * @private
-     * @param {*} value The value to inspect.
-     * @returns {string|symbol} Returns the key.
-     */
-    function toKey(value) {
-      if (typeof value == 'string' || isSymbol(value)) {
-        return value;
-      }
-      var result = (value + '');
-      return (result == '0' && (1 / value) == -INFINITY$2) ? '-0' : result;
-    }
-
-    /**
-     * The base implementation of `_.get` without support for default values.
-     *
-     * @private
-     * @param {Object} object The object to query.
-     * @param {Array|string} path The path of the property to get.
-     * @returns {*} Returns the resolved value.
-     */
-    function baseGet(object, path) {
-      path = isKey(path, object) ? [path] : castPath(path);
-
-      var index = 0,
-          length = path.length;
-
-      while (object != null && index < length) {
-        object = object[toKey(path[index++])];
-      }
-      return (index && index == length) ? object : undefined;
-    }
-
-    /**
-     * Gets the value at `path` of `object`. If the resolved value is
-     * `undefined`, the `defaultValue` is used in its place.
-     *
-     * @static
-     * @memberOf _
-     * @since 3.7.0
-     * @category Object
-     * @param {Object} object The object to query.
-     * @param {Array|string} path The path of the property to get.
-     * @param {*} [defaultValue] The value returned for `undefined` resolved values.
-     * @returns {*} Returns the resolved value.
-     * @example
-     *
-     * var object = { 'a': [{ 'b': { 'c': 3 } }] };
-     *
-     * _.get(object, 'a[0].b.c');
-     * // => 3
-     *
-     * _.get(object, ['a', '0', 'b', 'c']);
-     * // => 3
-     *
-     * _.get(object, 'a.b.c', 'default');
-     * // => 'default'
-     */
-    function get(object, path, defaultValue) {
-      var result = object == null ? undefined : baseGet(object, path);
-      return result === undefined ? defaultValue : result;
-    }
-
-    /**
-     * The base implementation of `_.hasIn` without support for deep paths.
-     *
-     * @private
-     * @param {Object} [object] The object to query.
-     * @param {Array|string} key The key to check.
-     * @returns {boolean} Returns `true` if `key` exists, else `false`.
-     */
-    function baseHasIn(object, key) {
-      return object != null && key in Object(object);
-    }
-
-    /**
-     * Checks if `path` exists on `object`.
-     *
-     * @private
-     * @param {Object} object The object to query.
-     * @param {Array|string} path The path to check.
-     * @param {Function} hasFunc The function to check properties.
-     * @returns {boolean} Returns `true` if `path` exists, else `false`.
-     */
-    function hasPath(object, path, hasFunc) {
-      path = isKey(path, object) ? [path] : castPath(path);
-
-      var result,
-          index = -1,
-          length = path.length;
-
-      while (++index < length) {
-        var key = toKey(path[index]);
-        if (!(result = object != null && hasFunc(object, key))) {
-          break;
-        }
-        object = object[key];
-      }
-      if (result) {
-        return result;
-      }
-      var length = object ? object.length : 0;
-      return !!length && isLength(length) && isIndex(key, length) &&
-        (isArray(object) || isString(object) || isArguments(object));
-    }
-
-    /**
-     * Checks if `path` is a direct or inherited property of `object`.
-     *
-     * @static
-     * @memberOf _
-     * @since 4.0.0
-     * @category Object
-     * @param {Object} object The object to query.
-     * @param {Array|string} path The path to check.
-     * @returns {boolean} Returns `true` if `path` exists, else `false`.
-     * @example
-     *
-     * var object = _.create({ 'a': _.create({ 'b': 2 }) });
-     *
-     * _.hasIn(object, 'a');
-     * // => true
-     *
-     * _.hasIn(object, 'a.b');
-     * // => true
-     *
-     * _.hasIn(object, ['a', 'b']);
-     * // => true
-     *
-     * _.hasIn(object, 'b');
-     * // => false
-     */
-    function hasIn(object, path) {
-      return object != null && hasPath(object, path, baseHasIn);
-    }
-
-    var UNORDERED_COMPARE_FLAG$3 = 1;
-    var PARTIAL_COMPARE_FLAG$5 = 2;
-    /**
-     * The base implementation of `_.matchesProperty` which doesn't clone `srcValue`.
-     *
-     * @private
-     * @param {string} path The path of the property to get.
-     * @param {*} srcValue The value to match.
-     * @returns {Function} Returns the new spec function.
-     */
-    function baseMatchesProperty(path, srcValue) {
-      if (isKey(path) && isStrictComparable(srcValue)) {
-        return matchesStrictComparable(toKey(path), srcValue);
+  }
+
+  var slice = Array.prototype.slice;
+
+  /**
+   * Same as [`reduce`]{@link module:Collections.reduce}, only operates on `coll` in reverse order.
+   *
+   * @name reduceRight
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.reduce]{@link module:Collections.reduce}
+   * @alias foldr
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {*} memo - The initial state of the reduction.
+   * @param {Function} iteratee - A function applied to each item in the
+   * array to produce the next step in the reduction. The `iteratee` is passed a
+   * `callback(err, reduction)` which accepts an optional error as its first
+   * argument, and the state of the reduction as the second. If an error is
+   * passed to the callback, the reduction is stopped and the main `callback` is
+   * immediately called with the error. Invoked with (memo, item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Result is the reduced value. Invoked with
+   * (err, result).
+   */
+  function reduceRight(coll, memo, iteratee, callback) {
+    var reversed = slice.call(coll).reverse();
+    reduce(reversed, memo, iteratee, callback);
+  }
+
+  /**
+   * Wraps the function in another function that always returns data even when it
+   * errors.
+   *
+   * The object returned has either the property `error` or `value`.
+   *
+   * @name reflect
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {Function} fn - The function you want to wrap
+   * @returns {Function} - A function that always passes null to it's callback as
+   * the error. The second argument to the callback will be an `object` with
+   * either an `error` or a `value` property.
+   * @example
+   *
+   * async.parallel([
+   *     async.reflect(function(callback) {
+   *         // do some stuff ...
+   *         callback(null, 'one');
+   *     }),
+   *     async.reflect(function(callback) {
+   *         // do some more stuff but error ...
+   *         callback('bad stuff happened');
+   *     }),
+   *     async.reflect(function(callback) {
+   *         // do some more stuff ...
+   *         callback(null, 'two');
+   *     })
+   * ],
+   * // optional callback
+   * function(err, results) {
+   *     // values
+   *     // results[0].value = 'one'
+   *     // results[1].error = 'bad stuff happened'
+   *     // results[2].value = 'two'
+   * });
+   */
+  function reflect(fn) {
+      return initialParams(function reflectOn(args, reflectCallback) {
+          args.push(rest(function callback(err, cbArgs) {
+              if (err) {
+                  reflectCallback(null, {
+                      error: err
+                  });
+              } else {
+                  var value = null;
+                  if (cbArgs.length === 1) {
+                      value = cbArgs[0];
+                  } else if (cbArgs.length > 1) {
+                      value = cbArgs;
+                  }
+                  reflectCallback(null, {
+                      value: value
+                  });
+              }
+          }));
+
+          return fn.apply(this, args);
+      });
+  }
+
+  function reject$1(eachfn, arr, iteratee, callback) {
+      _filter(eachfn, arr, function (value, cb) {
+          iteratee(value, function (err, v) {
+              if (err) {
+                  cb(err);
+              } else {
+                  cb(null, !v);
+              }
+          });
+      }, callback);
+  }
+
+  /**
+   * The same as [`reject`]{@link module:Collections.reject} but runs a maximum of `limit` async operations at a
+   * time.
+   *
+   * @name rejectLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.reject]{@link module:Collections.reject}
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Invoked with (err, results).
+   */
+  var rejectLimit = doParallelLimit(reject$1);
+
+  /**
+   * The opposite of [`filter`]{@link module:Collections.filter}. Removes values that pass an `async` truth test.
+   *
+   * @name reject
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.filter]{@link module:Collections.filter}
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Invoked with (err, results).
+   * @example
+   *
+   * async.reject(['file1','file2','file3'], function(filePath, callback) {
+   *     fs.access(filePath, function(err) {
+   *         callback(null, !err)
+   *     });
+   * }, function(err, results) {
+   *     // results now equals an array of missing files
+   *     createFiles(results);
+   * });
+   */
+  var reject = doLimit(rejectLimit, Infinity);
+
+  /**
+   * A helper function that wraps an array or an object of functions with reflect.
+   *
+   * @name reflectAll
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @see [async.reflect]{@link module:Utils.reflect}
+   * @category Util
+   * @param {Array} tasks - The array of functions to wrap in `async.reflect`.
+   * @returns {Array} Returns an array of functions, each function wrapped in
+   * `async.reflect`
+   * @example
+   *
+   * let tasks = [
+   *     function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'one');
+   *         }, 200);
+   *     },
+   *     function(callback) {
+   *         // do some more stuff but error ...
+   *         callback(new Error('bad stuff happened'));
+   *     },
+   *     function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'two');
+   *         }, 100);
+   *     }
+   * ];
+   *
+   * async.parallel(async.reflectAll(tasks),
+   * // optional callback
+   * function(err, results) {
+   *     // values
+   *     // results[0].value = 'one'
+   *     // results[1].error = Error('bad stuff happened')
+   *     // results[2].value = 'two'
+   * });
+   *
+   * // an example using an object instead of an array
+   * let tasks = {
+   *     one: function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'one');
+   *         }, 200);
+   *     },
+   *     two: function(callback) {
+   *         callback('two');
+   *     },
+   *     three: function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 'three');
+   *         }, 100);
+   *     }
+   * };
+   *
+   * async.parallel(async.reflectAll(tasks),
+   * // optional callback
+   * function(err, results) {
+   *     // values
+   *     // results.one.value = 'one'
+   *     // results.two.error = 'two'
+   *     // results.three.value = 'three'
+   * });
+   */
+  function reflectAll(tasks) {
+      var results;
+      if (isArray(tasks)) {
+          results = arrayMap(tasks, reflect);
+      } else {
+          results = {};
+          baseForOwn(tasks, function (task, key) {
+              results[key] = reflect.call(this, task);
+          });
       }
-      return function(object) {
-        var objValue = get(object, path);
-        return (objValue === undefined && objValue === srcValue)
-          ? hasIn(object, path)
-          : baseIsEqual(srcValue, objValue, undefined, UNORDERED_COMPARE_FLAG$3 | PARTIAL_COMPARE_FLAG$5);
-      };
-    }
-
-    /**
-     * This method returns the first argument given to it.
-     *
-     * @static
-     * @since 0.1.0
-     * @memberOf _
-     * @category Util
-     * @param {*} value Any value.
-     * @returns {*} Returns `value`.
-     * @example
-     *
-     * var object = { 'user': 'fred' };
-     *
-     * console.log(_.identity(object) === object);
-     * // => true
-     */
-    function identity(value) {
+      return results;
+  }
+
+  /**
+   * The same as [`reject`]{@link module:Collections.reject} but runs only a single async operation at a time.
+   *
+   * @name rejectSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.reject]{@link module:Collections.reject}
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in `coll`.
+   * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
+   * with a boolean argument once it has completed. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Invoked with (err, results).
+   */
+  var rejectSeries = doLimit(rejectLimit, 1);
+
+  /**
+   * Run the functions in the `tasks` collection in series, each one running once
+   * the previous function has completed. If any functions in the series pass an
+   * error to its callback, no more functions are run, and `callback` is
+   * immediately called with the value of the error. Otherwise, `callback`
+   * receives an array of results when `tasks` have completed.
+   *
+   * It is also possible to use an object instead of an array. Each property will
+   * be run as a function, and the results will be passed to the final `callback`
+   * as an object instead of an array. This can be a more readable way of handling
+   *  results from {@link async.series}.
+   *
+   * **Note** that while many implementations preserve the order of object
+   * properties, the [ECMAScript Language Specification](http://www.ecma-international.org/ecma-262/5.1/#sec-8.6)
+   * explicitly states that
+   *
+   * > The mechanics and order of enumerating the properties is not specified.
+   *
+   * So if you rely on the order in which your series of functions are executed,
+   * and want this to work on all platforms, consider using an array.
+   *
+   * @name series
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Array|Object} tasks - A collection containing functions to run, each
+   * function is passed a `callback(err, result)` it must call on completion with
+   * an error `err` (which can be `null`) and an optional `result` value.
+   * @param {Function} [callback] - An optional callback to run once all the
+   * functions have completed. This function gets a results array (or object)
+   * containing all the result arguments passed to the `task` callbacks. Invoked
+   * with (err, result).
+   * @example
+   * async.series([
+   *     function(callback) {
+   *         // do some stuff ...
+   *         callback(null, 'one');
+   *     },
+   *     function(callback) {
+   *         // do some more stuff ...
+   *         callback(null, 'two');
+   *     }
+   * ],
+   * // optional callback
+   * function(err, results) {
+   *     // results is now equal to ['one', 'two']
+   * });
+   *
+   * async.series({
+   *     one: function(callback) {
+   *         setTimeout(function() {
+   *             callback(null, 1);
+   *         }, 200);
+   *     },
+   *     two: function(callback){
+   *         setTimeout(function() {
+   *             callback(null, 2);
+   *         }, 100);
+   *     }
+   * }, function(err, results) {
+   *     // results is now equal to: {one: 1, two: 2}
+   * });
+   */
+  function series(tasks, callback) {
+    _parallel(eachOfSeries, tasks, callback);
+  }
+
+  /**
+   * Creates a function that returns `value`.
+   *
+   * @static
+   * @memberOf _
+   * @since 2.4.0
+   * @category Util
+   * @param {*} value The value to return from the new function.
+   * @returns {Function} Returns the new constant function.
+   * @example
+   *
+   * var objects = _.times(2, _.constant({ 'a': 1 }));
+   *
+   * console.log(objects);
+   * // => [{ 'a': 1 }, { 'a': 1 }]
+   *
+   * console.log(objects[0] === objects[1]);
+   * // => true
+   */
+  function constant$1(value) {
+    return function() {
       return value;
-    }
-
-    /**
-     * A specialized version of `baseProperty` which supports deep paths.
-     *
-     * @private
-     * @param {Array|string} path The path of the property to get.
-     * @returns {Function} Returns the new accessor function.
-     */
-    function basePropertyDeep(path) {
-      return function(object) {
-        return baseGet(object, path);
+    };
+  }
+
+  /**
+   * Attempts to get a successful response from `task` no more than `times` times
+   * before returning an error. If the task is successful, the `callback` will be
+   * passed the result of the successful task. If all attempts fail, the callback
+   * will be passed the error and result (if any) of the final attempt.
+   *
+   * @name retry
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Object|number} [opts = {times: 5, interval: 0}| 5] - Can be either an
+   * object with `times` and `interval` or a number.
+   * * `times` - The number of attempts to make before giving up.  The default
+   *   is `5`.
+   * * `interval` - The time to wait between retries, in milliseconds.  The
+   *   default is `0`. The interval may also be specified as a function of the
+   *   retry count (see example).
+   * * If `opts` is a number, the number specifies the number of times to retry,
+   *   with the default interval of `0`.
+   * @param {Function} task - A function which receives two arguments: (1) a
+   * `callback(err, result)` which must be called when finished, passing `err`
+   * (which can be `null`) and the `result` of the function's execution, and (2)
+   * a `results` object, containing the results of the previously executed
+   * functions (if nested inside another control flow). Invoked with
+   * (callback, results).
+   * @param {Function} [callback] - An optional callback which is called when the
+   * task has succeeded, or after the final failed attempt. It receives the `err`
+   * and `result` arguments of the last attempt at completing the `task`. Invoked
+   * with (err, results).
+   * @example
+   *
+   * // The `retry` function can be used as a stand-alone control flow by passing
+   * // a callback, as shown below:
+   *
+   * // try calling apiMethod 3 times
+   * async.retry(3, apiMethod, function(err, result) {
+   *     // do something with the result
+   * });
+   *
+   * // try calling apiMethod 3 times, waiting 200 ms between each retry
+   * async.retry({times: 3, interval: 200}, apiMethod, function(err, result) {
+   *     // do something with the result
+   * });
+   *
+   * // try calling apiMethod 10 times with exponential backoff
+   * // (i.e. intervals of 100, 200, 400, 800, 1600, ... milliseconds)
+   * async.retry({
+   *   times: 10,
+   *   interval: function(retryCount) {
+   *     return 50 * Math.pow(2, retryCount);
+   *   }
+   * }, apiMethod, function(err, result) {
+   *     // do something with the result
+   * });
+   *
+   * // try calling apiMethod the default 5 times no delay between each retry
+   * async.retry(apiMethod, function(err, result) {
+   *     // do something with the result
+   * });
+   *
+   * // It can also be embedded within other control flow functions to retry
+   * // individual methods that are not as reliable, like this:
+   * async.auto({
+   *     users: api.getUsers.bind(api),
+   *     payments: async.retry(3, api.getPayments.bind(api))
+   * }, function(err, results) {
+   *     // do something with the results
+   * });
+   */
+  function retry(opts, task, callback) {
+      var DEFAULT_TIMES = 5;
+      var DEFAULT_INTERVAL = 0;
+
+      var options = {
+          times: DEFAULT_TIMES,
+          intervalFunc: constant$1(DEFAULT_INTERVAL)
       };
-    }
 
-    /**
-     * Creates a function that returns the value at `path` of a given object.
-     *
-     * @static
-     * @memberOf _
-     * @since 2.4.0
-     * @category Util
-     * @param {Array|string} path The path of the property to get.
-     * @returns {Function} Returns the new accessor function.
-     * @example
-     *
-     * var objects = [
-     *   { 'a': { 'b': 2 } },
-     *   { 'a': { 'b': 1 } }
-     * ];
-     *
-     * _.map(objects, _.property('a.b'));
-     * // => [2, 1]
-     *
-     * _.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');
-     * // => [1, 2]
-     */
-    function property(path) {
-      return isKey(path) ? baseProperty(toKey(path)) : basePropertyDeep(path);
-    }
+      function parseTimes(acc, t) {
+          if (typeof t === 'object') {
+              acc.times = +t.times || DEFAULT_TIMES;
 
-    /**
-     * The base implementation of `_.iteratee`.
-     *
-     * @private
-     * @param {*} [value=_.identity] The value to convert to an iteratee.
-     * @returns {Function} Returns the iteratee.
-     */
-    function baseIteratee(value) {
-      // Don't store the `typeof` result in a variable to avoid a JIT bug in Safari 9.
-      // See https://bugs.webkit.org/show_bug.cgi?id=156034 for more details.
-      if (typeof value == 'function') {
-        return value;
-      }
-      if (value == null) {
-        return identity;
-      }
-      if (typeof value == 'object') {
-        return isArray(value)
-          ? baseMatchesProperty(value[0], value[1])
-          : baseMatches(value);
-      }
-      return property(value);
-    }
-
-    /**
-     * Iterates over own enumerable string keyed properties of an object and
-     * invokes `iteratee` for each property. The iteratee is invoked with three
-     * arguments: (value, key, object). Iteratee functions may exit iteration
-     * early by explicitly returning `false`.
-     *
-     * @static
-     * @memberOf _
-     * @since 0.3.0
-     * @category Object
-     * @param {Object} object The object to iterate over.
-     * @param {Function} [iteratee=_.identity] The function invoked per iteration.
-     * @returns {Object} Returns `object`.
-     * @see _.forOwnRight
-     * @example
-     *
-     * function Foo() {
-     *   this.a = 1;
-     *   this.b = 2;
-     * }
-     *
-     * Foo.prototype.c = 3;
-     *
-     * _.forOwn(new Foo, function(value, key) {
-     *   console.log(key);
-     * });
-     * // => Logs 'a' then 'b' (iteration order is not guaranteed).
-     */
-    function forOwn(object, iteratee) {
-      return object && baseForOwn(object, baseIteratee(iteratee, 3));
-    }
-
-    /**
-     * Gets the index at which the first occurrence of `NaN` is found in `array`.
-     *
-     * @private
-     * @param {Array} array The array to search.
-     * @param {number} fromIndex The index to search from.
-     * @param {boolean} [fromRight] Specify iterating from right to left.
-     * @returns {number} Returns the index of the matched `NaN`, else `-1`.
-     */
-    function indexOfNaN(array, fromIndex, fromRight) {
-      var length = array.length,
-          index = fromIndex + (fromRight ? 1 : -1);
-
-      while ((fromRight ? index-- : ++index < length)) {
-        var other = array[index];
-        if (other !== other) {
-          return index;
-        }
+              acc.intervalFunc = typeof t.interval === 'function' ? t.interval : constant$1(+t.interval || DEFAULT_INTERVAL);
+          } else if (typeof t === 'number' || typeof t === 'string') {
+              acc.times = +t || DEFAULT_TIMES;
+          } else {
+              throw new Error("Invalid arguments for async.retry");
+          }
       }
-      return -1;
-    }
 
-    /**
-     * The base implementation of `_.indexOf` without `fromIndex` bounds checks.
-     *
-     * @private
-     * @param {Array} array The array to search.
-     * @param {*} value The value to search for.
-     * @param {number} fromIndex The index to search from.
-     * @returns {number} Returns the index of the matched value, else `-1`.
-     */
-    function baseIndexOf(array, value, fromIndex) {
-      if (value !== value) {
-        return indexOfNaN(array, fromIndex);
+      if (arguments.length < 3 && typeof opts === 'function') {
+          callback = task || noop;
+          task = opts;
+      } else {
+          parseTimes(options, opts);
+          callback = callback || noop;
       }
-      var index = fromIndex - 1,
-          length = array.length;
 
-      while (++index < length) {
-        if (array[index] === value) {
-          return index;
-        }
+      if (typeof task !== 'function') {
+          throw new Error("Invalid arguments for async.retry");
       }
-      return -1;
-    }
-
-    /**
-     * Determines the best order for running the functions in `tasks`, based on
-     * their requirements. Each function can optionally depend on other functions
-     * being completed first, and each function is run as soon as its requirements
-     * are satisfied.
-     *
-     * If any of the functions pass an error to their callback, the `auto` sequence
-     * will stop. Further tasks will not execute (so any other functions depending
-     * on it will not run), and the main `callback` is immediately called with the
-     * error.
-     *
-     * Functions also receive an object containing the results of functions which
-     * have completed so far as the first argument, if they have dependencies. If a
-     * task function has no dependencies, it will only be passed a callback.
-     *
-     * @name auto
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Object} tasks - An object. Each of its properties is either a
-     * function or an array of requirements, with the function itself the last item
-     * in the array. The object's key of a property serves as the name of the task
-     * defined by that property, i.e. can be used when specifying requirements for
-     * other tasks. The function receives one or two arguments:
-     * * a `results` object, containing the results of the previously executed
-     *   functions, only passed if the task has any dependencies,
-     * * a `callback(err, result)` function, which must be called when finished,
-     *   passing an `error` (which can be `null`) and the result of the function's
-     *   execution.
-     * @param {number} [concurrency=Infinity] - An optional `integer` for
-     * determining the maximum number of tasks that can be run in parallel. By
-     * default, as many as possible.
-     * @param {Function} [callback] - An optional callback which is called when all
-     * the tasks have been completed. It receives the `err` argument if any `tasks`
-     * pass an error to their callback. Results are always returned; however, if an
-     * error occurs, no further `tasks` will be performed, and the results object
-     * will only contain partial results. Invoked with (err, results).
-     * @example
-     *
-     * async.auto({
-     *     // this function will just be passed a callback
-     *     readData: async.apply(fs.readFile, 'data.txt', 'utf-8'),
-     *     showData: ['readData', function(results, cb) {
-     *         // results.readData is the file's contents
-     *         // ...
-     *     }]
-     * }, callback);
-     *
-     * async.auto({
-     *     get_data: function(callback) {
-     *         console.log('in get_data');
-     *         // async code to get some data
-     *         callback(null, 'data', 'converted to array');
-     *     },
-     *     make_folder: function(callback) {
-     *         console.log('in make_folder');
-     *         // async code to create a directory to store a file in
-     *         // this is run at the same time as getting the data
-     *         callback(null, 'folder');
-     *     },
-     *     write_file: ['get_data', 'make_folder', function(results, callback) {
-     *         console.log('in write_file', JSON.stringify(results));
-     *         // once there is some data and the directory exists,
-     *         // write the data to a file in the directory
-     *         callback(null, 'filename');
-     *     }],
-     *     email_link: ['write_file', function(results, callback) {
-     *         console.log('in email_link', JSON.stringify(results));
-     *         // once the file is written let's email a link to it...
-     *         // results.write_file contains the filename returned by write_file.
-     *         callback(null, {'file':results.write_file, 'email':'user@example.com'});
-     *     }]
-     * }, function(err, results) {
-     *     console.log('err = ', err);
-     *     console.log('results = ', results);
-     * });
-     */
-    function auto (tasks, concurrency, callback) {
-        if (typeof concurrency === 'function') {
-            // concurrency is optional, shift the args.
-            callback = concurrency;
-            concurrency = null;
-        }
-        callback = once(callback || noop);
-        var keys$$ = keys(tasks);
-        var numTasks = keys$$.length;
-        if (!numTasks) {
-            return callback(null);
-        }
-        if (!concurrency) {
-            concurrency = numTasks;
-        }
-
-        var results = {};
-        var runningTasks = 0;
-        var hasError = false;
-
-        var listeners = {};
-
-        var readyTasks = [];
-
-        // for cycle detection:
-        var readyToCheck = []; // tasks that have been identified as reachable
-        // without the possibility of returning to an ancestor task
-        var uncheckedDependencies = {};
-
-        forOwn(tasks, function (task, key) {
-            if (!isArray(task)) {
-                // no dependencies
-                enqueueTask(key, [task]);
-                readyToCheck.push(key);
-                return;
-            }
-
-            var dependencies = task.slice(0, task.length - 1);
-            var remainingDependencies = dependencies.length;
-            if (remainingDependencies === 0) {
-                enqueueTask(key, task);
-                readyToCheck.push(key);
-                return;
-            }
-            uncheckedDependencies[key] = remainingDependencies;
-
-            arrayEach(dependencies, function (dependencyName) {
-                if (!tasks[dependencyName]) {
-                    throw new Error('async.auto task `' + key + '` has a non-existent dependency in ' + dependencies.join(', '));
-                }
-                addListener(dependencyName, function () {
-                    remainingDependencies--;
-                    if (remainingDependencies === 0) {
-                        enqueueTask(key, task);
-                    }
-                });
-            });
-        });
-
-        checkForDeadlocks();
-        processQueue();
-
-        function enqueueTask(key, task) {
-            readyTasks.push(function () {
-                runTask(key, task);
-            });
-        }
-
-        function processQueue() {
-            if (readyTasks.length === 0 && runningTasks === 0) {
-                return callback(null, results);
-            }
-            while (readyTasks.length && runningTasks < concurrency) {
-                var run = readyTasks.shift();
-                run();
-            }
-        }
-
-        function addListener(taskName, fn) {
-            var taskListeners = listeners[taskName];
-            if (!taskListeners) {
-                taskListeners = listeners[taskName] = [];
-            }
-
-            taskListeners.push(fn);
-        }
 
-        function taskComplete(taskName) {
-            var taskListeners = listeners[taskName] || [];
-            arrayEach(taskListeners, function (fn) {
-                fn();
-            });
-            processQueue();
-        }
-
-        function runTask(key, task) {
-            if (hasError) return;
-
-            var taskCallback = onlyOnce(rest(function (err, args) {
-                runningTasks--;
-                if (args.length <= 1) {
-                    args = args[0];
-                }
-                if (err) {
-                    var safeResults = {};
-                    forOwn(results, function (val, rkey) {
-                        safeResults[rkey] = val;
-                    });
-                    safeResults[key] = args;
-                    hasError = true;
-                    listeners = [];
-
-                    callback(err, safeResults);
-                } else {
-                    results[key] = args;
-                    taskComplete(key);
-                }
-            }));
-
-            runningTasks++;
-            var taskFn = task[task.length - 1];
-            if (task.length > 1) {
-                taskFn(results, taskCallback);
-            } else {
-                taskFn(taskCallback);
-            }
-        }
-
-        function checkForDeadlocks() {
-            // Kahn's algorithm
-            // https://en.wikipedia.org/wiki/Topological_sorting#Kahn.27s_algorithm
-            // http://connalle.blogspot.com/2013/10/topological-sortingkahn-algorithm.html
-            var currentTask;
-            var counter = 0;
-            while (readyToCheck.length) {
-                currentTask = readyToCheck.pop();
-                counter++;
-                arrayEach(getDependents(currentTask), function (dependent) {
-                    if (! --uncheckedDependencies[dependent]) {
-                        readyToCheck.push(dependent);
-                    }
-                });
-            }
-
-            if (counter !== numTasks) {
-                throw new Error('async.auto cannot execute tasks due to a recursive dependency');
-            }
-        }
-
-        function getDependents(taskName) {
-            var result = [];
-            forOwn(tasks, function (task, key) {
-                if (isArray(task) && baseIndexOf(task, taskName, 0) >= 0) {
-                    result.push(key);
-                }
-            });
-            return result;
-        }
-    }
-
-    /**
-     * A specialized version of `_.map` for arrays without support for iteratee
-     * shorthands.
-     *
-     * @private
-     * @param {Array} [array] The array to iterate over.
-     * @param {Function} iteratee The function invoked per iteration.
-     * @returns {Array} Returns the new mapped array.
-     */
-    function arrayMap(array, iteratee) {
-      var index = -1,
-          length = array ? array.length : 0,
-          result = Array(length);
-
-      while (++index < length) {
-        result[index] = iteratee(array[index], index, array);
+      var attempts = [];
+      for (var i = 1; i < options.times + 1; i++) {
+          var isFinalAttempt = i == options.times;
+          attempts.push(retryAttempt(isFinalAttempt));
+          var interval = options.intervalFunc(i);
+          if (!isFinalAttempt && interval > 0) {
+              attempts.push(retryInterval(interval));
+          }
       }
-      return result;
-    }
 
-    /**
-     * Copies the values of `source` to `array`.
-     *
-     * @private
-     * @param {Array} source The array to copy values from.
-     * @param {Array} [array=[]] The array to copy values to.
-     * @returns {Array} Returns `array`.
-     */
-    function copyArray(source, array) {
-      var index = -1,
-          length = source.length;
+      series(attempts, function (done, data) {
+          data = data[data.length - 1];
+          callback(data.err, data.result);
+      });
 
-      array || (array = Array(length));
-      while (++index < length) {
-        array[index] = source[index];
+      function retryAttempt(isFinalAttempt) {
+          return function (seriesCallback) {
+              task(function (err, result) {
+                  seriesCallback(!err || isFinalAttempt, {
+                      err: err,
+                      result: result
+                  });
+              });
+          };
       }
-      return array;
-    }
 
-    /**
-     * The base implementation of `_.slice` without an iteratee call guard.
-     *
-     * @private
-     * @param {Array} array The array to slice.
-     * @param {number} [start=0] The start position.
-     * @param {number} [end=array.length] The end position.
-     * @returns {Array} Returns the slice of `array`.
-     */
-    function baseSlice(array, start, end) {
-      var index = -1,
-          length = array.length;
-
-      if (start < 0) {
-        start = -start > length ? 0 : (length + start);
-      }
-      end = end > length ? length : end;
-      if (end < 0) {
-        end += length;
+      function retryInterval(interval) {
+          return function (seriesCallback) {
+              setTimeout(function () {
+                  seriesCallback(null);
+              }, interval);
+          };
       }
-      length = start > end ? 0 : ((end - start) >>> 0);
-      start >>>= 0;
-
-      var result = Array(length);
-      while (++index < length) {
-        result[index] = array[index + start];
+  }
+
+  /**
+   * A close relative of [`retry`]{@link module:ControlFlow.retry}.  This method wraps a task and makes it
+   * retryable, rather than immediately calling it with retries.
+   *
+   * @name retryable
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.retry]{@link module:ControlFlow.retry}
+   * @category Control Flow
+   * @param {Object|number} [opts = {times: 5, interval: 0}| 5] - optional
+   * options, exactly the same as from `retry`
+   * @param {Function} task - the asynchronous function to wrap
+   * @returns {Functions} The wrapped function, which when invoked, will retry on
+   * an error, based on the parameters specified in `opts`.
+   * @example
+   *
+   * async.auto({
+   *     dep1: async.retryable(3, getFromFlakyService),
+   *     process: ["dep1", async.retryable(3, function (results, cb) {
+   *         maybeProcessData(results.dep1, cb);
+   *     })]
+   * }, callback);
+   */
+  function retryable (opts, task) {
+      if (!task) {
+          task = opts;
+          opts = null;
       }
-      return result;
-    }
-
-    /**
-     * Casts `array` to a slice if it's needed.
-     *
-     * @private
-     * @param {Array} array The array to inspect.
-     * @param {number} start The start position.
-     * @param {number} [end=array.length] The end position.
-     * @returns {Array} Returns the cast slice.
-     */
-    function castSlice(array, start, end) {
-      var length = array.length;
-      end = end === undefined ? length : end;
-      return (!start && end >= length) ? array : baseSlice(array, start, end);
-    }
-
-    /**
-     * Used by `_.trim` and `_.trimEnd` to get the index of the last string symbol
-     * that is not found in the character symbols.
-     *
-     * @private
-     * @param {Array} strSymbols The string symbols to inspect.
-     * @param {Array} chrSymbols The character symbols to find.
-     * @returns {number} Returns the index of the last unmatched string symbol.
-     */
-    function charsEndIndex(strSymbols, chrSymbols) {
-      var index = strSymbols.length;
-
-      while (index-- && baseIndexOf(chrSymbols, strSymbols[index], 0) > -1) {}
-      return index;
-    }
-
-    /**
-     * Used by `_.trim` and `_.trimStart` to get the index of the first string symbol
-     * that is not found in the character symbols.
-     *
-     * @private
-     * @param {Array} strSymbols The string symbols to inspect.
-     * @param {Array} chrSymbols The character symbols to find.
-     * @returns {number} Returns the index of the first unmatched string symbol.
-     */
-    function charsStartIndex(strSymbols, chrSymbols) {
-      var index = -1,
-          length = strSymbols.length;
-
-      while (++index < length && baseIndexOf(chrSymbols, strSymbols[index], 0) > -1) {}
-      return index;
-    }
+      return initialParams(function (args, callback) {
+          function taskFn(cb) {
+              task.apply(null, args.concat([cb]));
+          }
 
-    /** Used to compose unicode character classes. */
-    var rsAstralRange = '\\ud800-\\udfff';
-    var rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23';
-    var rsComboSymbolsRange = '\\u20d0-\\u20f0';
-    var rsVarRange = '\\ufe0e\\ufe0f';
-    var rsAstral = '[' + rsAstralRange + ']';
-    var rsCombo = '[' + rsComboMarksRange + rsComboSymbolsRange + ']';
-    var rsFitz = '\\ud83c[\\udffb-\\udfff]';
-    var rsModifier = '(?:' + rsCombo + '|' + rsFitz + ')';
-    var rsNonAstral = '[^' + rsAstralRange + ']';
-    var rsRegional = '(?:\\ud83c[\\udde6-\\uddff]){2}';
-    var rsSurrPair = '[\\ud800-\\udbff][\\udc00-\\udfff]';
-    var rsZWJ = '\\u200d';
-    var reOptMod = rsModifier + '?';
-    var rsOptVar = '[' + rsVarRange + ']?';
-    var rsOptJoin = '(?:' + rsZWJ + '(?:' + [rsNonAstral, rsRegional, rsSurrPair].join('|') + ')' + rsOptVar + reOptMod + ')*';
-    var rsSeq = rsOptVar + reOptMod + rsOptJoin;
-    var rsSymbol = '(?:' + [rsNonAstral + rsCombo + '?', rsCombo, rsRegional, rsSurrPair, rsAstral].join('|') + ')';
-    /** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
-    var reComplexSymbol = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq, 'g');
-
-    /**
-     * Converts `string` to an array.
-     *
-     * @private
-     * @param {string} string The string to convert.
-     * @returns {Array} Returns the converted array.
-     */
-    function stringToArray(string) {
-      return string.match(reComplexSymbol);
-    }
+          if (opts) retry(opts, taskFn, callback);else retry(taskFn, callback);
+      });
+  }
+
+  /**
+   * The same as [`some`]{@link module:Collections.some} but runs a maximum of `limit` async operations at a time.
+   *
+   * @name someLimit
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.some]{@link module:Collections.some}
+   * @alias anyLimit
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - A truth test to apply to each item in the array
+   * in parallel. The iteratee is passed a `callback(err, truthValue)` which must
+   * be called with a boolean argument once it has completed. Invoked with
+   * (item, callback).
+   * @param {Function} [callback] - A callback which is called as soon as any
+   * iteratee returns `true`, or after all the iteratee functions have finished.
+   * Result will be either `true` or `false` depending on the values of the async
+   * tests. Invoked with (err, result).
+   */
+  var someLimit = _createTester(eachOfLimit, Boolean, identity);
+
+  /**
+   * Returns `true` if at least one element in the `coll` satisfies an async test.
+   * If any iteratee call returns `true`, the main `callback` is immediately
+   * called.
+   *
+   * @name some
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @alias any
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in the array
+   * in parallel. The iteratee is passed a `callback(err, truthValue)` which must
+   * be called with a boolean argument once it has completed. Invoked with
+   * (item, callback).
+   * @param {Function} [callback] - A callback which is called as soon as any
+   * iteratee returns `true`, or after all the iteratee functions have finished.
+   * Result will be either `true` or `false` depending on the values of the async
+   * tests. Invoked with (err, result).
+   * @example
+   *
+   * async.some(['file1','file2','file3'], function(filePath, callback) {
+   *     fs.access(filePath, function(err) {
+   *         callback(null, !err)
+   *     });
+   * }, function(err, result) {
+   *     // if result is true then at least one of the files exists
+   * });
+   */
+  var some = doLimit(someLimit, Infinity);
+
+  /**
+   * The same as [`some`]{@link module:Collections.some} but runs only a single async operation at a time.
+   *
+   * @name someSeries
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @see [async.some]{@link module:Collections.some}
+   * @alias anySeries
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A truth test to apply to each item in the array
+   * in parallel. The iteratee is passed a `callback(err, truthValue)` which must
+   * be called with a boolean argument once it has completed. Invoked with
+   * (item, callback).
+   * @param {Function} [callback] - A callback which is called as soon as any
+   * iteratee returns `true`, or after all the iteratee functions have finished.
+   * Result will be either `true` or `false` depending on the values of the async
+   * tests. Invoked with (err, result).
+   */
+  var someSeries = doLimit(someLimit, 1);
+
+  /**
+   * Sorts a list by the results of running each `coll` value through an async
+   * `iteratee`.
+   *
+   * @name sortBy
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {Function} iteratee - A function to apply to each item in `coll`.
+   * The iteratee is passed a `callback(err, sortValue)` which must be called once
+   * it has completed with an error (which can be `null`) and a value to use as
+   * the sort criteria. Invoked with (item, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished, or an error occurs. Results is the items
+   * from the original `coll` sorted by the values returned by the `iteratee`
+   * calls. Invoked with (err, results).
+   * @example
+   *
+   * async.sortBy(['file1','file2','file3'], function(file, callback) {
+   *     fs.stat(file, function(err, stats) {
+   *         callback(err, stats.mtime);
+   *     });
+   * }, function(err, results) {
+   *     // results is now the original array of files sorted by
+   *     // modified date
+   * });
+   *
+   * // By modifying the callback parameter the
+   * // sorting order can be influenced:
+   *
+   * // ascending order
+   * async.sortBy([1,9,3,5], function(x, callback) {
+   *     callback(null, x);
+   * }, function(err,result) {
+   *     // result callback
+   * });
+   *
+   * // descending order
+   * async.sortBy([1,9,3,5], function(x, callback) {
+   *     callback(null, x*-1);    //<- x*-1 instead of x, turns the order around
+   * }, function(err,result) {
+   *     // result callback
+   * });
+   */
+  function sortBy(coll, iteratee, callback) {
+      map(coll, function (x, callback) {
+          iteratee(x, function (err, criteria) {
+              if (err) return callback(err);
+              callback(null, { value: x, criteria: criteria });
+          });
+      }, function (err, results) {
+          if (err) return callback(err);
+          callback(null, arrayMap(results.sort(comparator), baseProperty('value')));
+      });
 
-    /** Used to match leading and trailing whitespace. */
-    var reTrim$1 = /^\s+|\s+$/g;
-
-    /**
-     * Removes leading and trailing whitespace or specified characters from `string`.
-     *
-     * @static
-     * @memberOf _
-     * @since 3.0.0
-     * @category String
-     * @param {string} [string=''] The string to trim.
-     * @param {string} [chars=whitespace] The characters to trim.
-     * @param- {Object} [guard] Enables use as an iteratee for methods like `_.map`.
-     * @returns {string} Returns the trimmed string.
-     * @example
-     *
-     * _.trim('  abc  ');
-     * // => 'abc'
-     *
-     * _.trim('-_-abc-_-', '_-');
-     * // => 'abc'
-     *
-     * _.map(['  foo  ', '  bar  '], _.trim);
-     * // => ['foo', 'bar']
-     */
-    function trim(string, chars, guard) {
-      string = toString(string);
-      if (string && (guard || chars === undefined)) {
-        return string.replace(reTrim$1, '');
+      function comparator(left, right) {
+          var a = left.criteria,
+              b = right.criteria;
+          return a < b ? -1 : a > b ? 1 : 0;
       }
-      if (!string || !(chars = baseToString(chars))) {
-        return string;
+  }
+
+  /**
+   * Sets a time limit on an asynchronous function. If the function does not call
+   * its callback within the specified milliseconds, it will be called with a
+   * timeout error. The code property for the error object will be `'ETIMEDOUT'`.
+   *
+   * @name timeout
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @category Util
+   * @param {Function} asyncFn - The asynchronous function you want to set the
+   * time limit.
+   * @param {number} milliseconds - The specified time limit.
+   * @param {*} [info] - Any variable you want attached (`string`, `object`, etc)
+   * to timeout Error for more information..
+   * @returns {Function} Returns a wrapped function that can be used with any of
+   * the control flow functions.
+   * @example
+   *
+   * async.timeout(function(callback) {
+   *     doAsyncTask(callback);
+   * }, 1000);
+   */
+  function timeout(asyncFn, milliseconds, info) {
+      var originalCallback, timer;
+      var timedOut = false;
+
+      function injectedCallback() {
+          if (!timedOut) {
+              originalCallback.apply(null, arguments);
+              clearTimeout(timer);
+          }
       }
-      var strSymbols = stringToArray(string),
-          chrSymbols = stringToArray(chars),
-          start = charsStartIndex(strSymbols, chrSymbols),
-          end = charsEndIndex(strSymbols, chrSymbols) + 1;
-
-      return castSlice(strSymbols, start, end).join('');
-    }
-
-    var argsRegex = /^(function[^\(]*)?\(?\s*([^\)=]*)/m;
-
-    function parseParams(func) {
-        return trim(func.toString().match(argsRegex)[2]).split(/\s*\,\s*/);
-    }
-
-    /**
-     * A dependency-injected version of the {@link async.auto} function. Dependent
-     * tasks are specified as parameters to the function, after the usual callback
-     * parameter, with the parameter names matching the names of the tasks it
-     * depends on. This can provide even more readable task graphs which can be
-     * easier to maintain.
-     *
-     * If a final callback is specified, the task results are similarly injected,
-     * specified as named parameters after the initial error parameter.
-     *
-     * The autoInject function is purely syntactic sugar and its semantics are
-     * otherwise equivalent to {@link async.auto}.
-     *
-     * @name autoInject
-     * @static
-     * @memberOf async
-     * @see async.auto
-     * @category Control Flow
-     * @param {Object} tasks - An object, each of whose properties is a function of
-     * the form 'func([dependencies...], callback). The object's key of a property
-     * serves as the name of the task defined by that property, i.e. can be used
-     * when specifying requirements for other tasks.
-     * * The `callback` parameter is a `callback(err, result)` which must be called
-     *   when finished, passing an `error` (which can be `null`) and the result of
-     *   the function's execution. The remaining parameters name other tasks on
-     *   which the task is dependent, and the results from those tasks are the
-     *   arguments of those parameters.
-     * @param {Function} [callback] - An optional callback which is called when all
-     * the tasks have been completed. It receives the `err` argument if any `tasks`
-     * pass an error to their callback. The remaining parameters are task names
-     * whose results you are interested in. This callback will only be called when
-     * all tasks have finished or an error has occurred, and so do not specify
-     * dependencies in the same way as `tasks` do. If an error occurs, no further
-     * `tasks` will be performed, and `results` will only be valid for those tasks
-     * which managed to complete. Invoked with (err, [results...]).
-     * @example
-     *
-     * //  The example from `auto` can be rewritten as follows:
-     * async.autoInject({
-     *     get_data: function(callback) {
-     *         // async code to get some data
-     *         callback(null, 'data', 'converted to array');
-     *     },
-     *     make_folder: function(callback) {
-     *         // async code to create a directory to store a file in
-     *         // this is run at the same time as getting the data
-     *         callback(null, 'folder');
-     *     },
-     *     write_file: function(get_data, make_folder, callback) {
-     *         // once there is some data and the directory exists,
-     *         // write the data to a file in the directory
-     *         callback(null, 'filename');
-     *     },
-     *     email_link: function(write_file, callback) {
-     *         // once the file is written let's email a link to it...
-     *         // write_file contains the filename returned by write_file.
-     *         callback(null, {'file':write_file, 'email':'user@example.com'});
-     *     }
-     * }, function(err, email_link) {
-     *     console.log('err = ', err);
-     *     console.log('email_link = ', email_link);
-     * });
-     *
-     * // If you are using a JS minifier that mangles parameter names, `autoInject`
-     * // will not work with plain functions, since the parameter names will be
-     * // collapsed to a single letter identifier.  To work around this, you can
-     * // explicitly specify the names of the parameters your task function needs
-     * // in an array, similar to Angular.js dependency injection.  The final
-     * // results callback can be provided as an array in the same way.
-     *
-     * // This still has an advantage over plain `auto`, since the results a task
-     * // depends on are still spread into arguments.
-     * async.autoInject({
-     *     //...
-     *     write_file: ['get_data', 'make_folder', function(get_data, make_folder, callback) {
-     *         callback(null, 'filename');
-     *     }],
-     *     email_link: ['write_file', function(write_file, callback) {
-     *         callback(null, {'file':write_file, 'email':'user@example.com'});
-     *     }]
-     *     //...
-     * }, ['email_link', function(err, email_link) {
-     *     console.log('err = ', err);
-     *     console.log('email_link = ', email_link);
-     * }]);
-     */
-    function autoInject(tasks, callback) {
-        var newTasks = {};
-
-        forOwn(tasks, function (taskFn, key) {
-            var params;
-
-            if (isArray(taskFn)) {
-                params = copyArray(taskFn);
-                taskFn = params.pop();
-
-                newTasks[key] = params.concat(params.length > 0 ? newTask : taskFn);
-            } else if (taskFn.length === 0) {
-                throw new Error("autoInject task functions require explicit parameters.");
-            } else if (taskFn.length === 1) {
-                // no dependencies, use the function as-is
-                newTasks[key] = taskFn;
-            } else {
-                params = parseParams(taskFn);
-                params.pop();
-
-                newTasks[key] = params.concat(newTask);
-            }
-
-            function newTask(results, taskCb) {
-                var newArgs = arrayMap(params, function (name) {
-                    return results[name];
-                });
-                newArgs.push(taskCb);
-                taskFn.apply(null, newArgs);
-            }
-        });
-
-        auto(newTasks, callback);
-    }
-
-    var hasSetImmediate = typeof setImmediate === 'function' && setImmediate;
-    var hasNextTick = typeof process === 'object' && typeof process.nextTick === 'function';
-
-    function fallback(fn) {
-        setTimeout(fn, 0);
-    }
-
-    function wrap(defer) {
-        return rest(function (fn, args) {
-            defer(function () {
-                fn.apply(null, args);
-            });
-        });
-    }
-
-    var _defer;
-
-    if (hasSetImmediate) {
-        _defer = setImmediate;
-    } else if (hasNextTick) {
-        _defer = process.nextTick;
-    } else {
-        _defer = fallback;
-    }
-
-    var setImmediate$1 = wrap(_defer);
-
-    function queue(worker, concurrency, payload) {
-        if (concurrency == null) {
-            concurrency = 1;
-        } else if (concurrency === 0) {
-            throw new Error('Concurrency must not be zero');
-        }
-        function _insert(q, data, pos, callback) {
-            if (callback != null && typeof callback !== 'function') {
-                throw new Error('task callback must be a function');
-            }
-            q.started = true;
-            if (!isArray(data)) {
-                data = [data];
-            }
-            if (data.length === 0 && q.idle()) {
-                // call drain immediately if there are no tasks
-                return setImmediate$1(function () {
-                    q.drain();
-                });
-            }
-            arrayEach(data, function (task) {
-                var item = {
-                    data: task,
-                    callback: callback || noop
-                };
-
-                if (pos) {
-                    q.tasks.unshift(item);
-                } else {
-                    q.tasks.push(item);
-                }
-            });
-            setImmediate$1(q.process);
-        }
-        function _next(q, tasks) {
-            return function () {
-                workers -= 1;
-
-                var removed = false;
-                var args = arguments;
-                arrayEach(tasks, function (task) {
-                    arrayEach(workersList, function (worker, index) {
-                        if (worker === task && !removed) {
-                            workersList.splice(index, 1);
-                            removed = true;
-                        }
-                    });
-
-                    task.callback.apply(task, args);
-
-                    if (args[0] != null) {
-                        q.error(args[0], task.data);
-                    }
-                });
-
-                if (workers <= q.concurrency - q.buffer) {
-                    q.unsaturated();
-                }
-
-                if (q.tasks.length + workers === 0) {
-                    q.drain();
-                }
-                q.process();
-            };
-        }
-
-        var workers = 0;
-        var workersList = [];
-        var q = {
-            tasks: [],
-            concurrency: concurrency,
-            payload: payload,
-            saturated: noop,
-            unsaturated: noop,
-            buffer: concurrency / 4,
-            empty: noop,
-            drain: noop,
-            error: noop,
-            started: false,
-            paused: false,
-            push: function (data, callback) {
-                _insert(q, data, false, callback);
-            },
-            kill: function () {
-                q.drain = noop;
-                q.tasks = [];
-            },
-            unshift: function (data, callback) {
-                _insert(q, data, true, callback);
-            },
-            process: function () {
-                while (!q.paused && workers < q.concurrency && q.tasks.length) {
-
-                    var tasks = q.payload ? q.tasks.splice(0, q.payload) : q.tasks.splice(0, q.tasks.length);
-
-                    var data = arrayMap(tasks, baseProperty('data'));
-
-                    if (q.tasks.length === 0) {
-                        q.empty();
-                    }
-                    workers += 1;
-                    workersList.push(tasks[0]);
-
-                    if (workers === q.concurrency) {
-                        q.saturated();
-                    }
-
-                    var cb = onlyOnce(_next(q, tasks));
-                    worker(data, cb);
-                }
-            },
-            length: function () {
-                return q.tasks.length;
-            },
-            running: function () {
-                return workers;
-            },
-            workersList: function () {
-                return workersList;
-            },
-            idle: function () {
-                return q.tasks.length + workers === 0;
-            },
-            pause: function () {
-                q.paused = true;
-            },
-            resume: function () {
-                if (q.paused === false) {
-                    return;
-                }
-                q.paused = false;
-                var resumeCount = Math.min(q.concurrency, q.tasks.length);
-                // Need to call q.process once per concurrent
-                // worker to preserve full concurrency after pause
-                for (var w = 1; w <= resumeCount; w++) {
-                    setImmediate$1(q.process);
-                }
-            }
-        };
-        return q;
-    }
-
-    /**
-     * A cargo of tasks for the worker function to complete. Cargo inherits all of
-     * the same methods and event callbacks as {@link async.queue}.
-     * @typedef {Object} cargo
-     * @property {Function} length - A function returning the number of items
-     * waiting to be processed. Invoke with ().
-     * @property {number} payload - An `integer` for determining how many tasks
-     * should be process per round. This property can be changed after a `cargo` is
-     * created to alter the payload on-the-fly.
-     * @property {Function} push - Adds `task` to the `queue`. The callback is
-     * called once the `worker` has finished processing the task. Instead of a
-     * single task, an array of `tasks` can be submitted. The respective callback is
-     * used for every task in the list. Invoke with (task, [callback]).
-     * @property {Function} saturated - A callback that is called when the
-     * `queue.length()` hits the concurrency and further tasks will be queued.
-     * @property {Function} empty - A callback that is called when the last item
-     * from the `queue` is given to a `worker`.
-     * @property {Function} drain - A callback that is called when the last item
-     * from the `queue` has returned from the `worker`.
-     * @property {Function} idle - a function returning false if there are items
-     * waiting or being processed, or true if not. Invoke with ().
-     * @property {Function} pause - a function that pauses the processing of tasks
-     * until `resume()` is called. Invoke with ().
-     * @property {Function} resume - a function that resumes the processing of
-     * queued tasks when the queue is paused. Invoke with ().
-     * @property {Function} kill - a function that removes the `drain` callback and
-     * empties remaining tasks from the queue forcing it to go idle. Invoke with ().
-     */
-
-    /**
-     * Creates a `cargo` object with the specified payload. Tasks added to the
-     * cargo will be processed altogether (up to the `payload` limit). If the
-     * `worker` is in progress, the task is queued until it becomes available. Once
-     * the `worker` has completed some tasks, each callback of those tasks is
-     * called. Check out [these](https://camo.githubusercontent.com/6bbd36f4cf5b35a0f11a96dcd2e97711ffc2fb37/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313637363837312f36383130382f62626330636662302d356632392d313165322d393734662d3333393763363464633835382e676966) [animations](https://camo.githubusercontent.com/f4810e00e1c5f5f8addbe3e9f49064fd5d102699/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313637363837312f36383130312f38346339323036362d356632392d313165322d383134662d3964336430323431336266642e676966)
-     * for how `cargo` and `queue` work.
-     *
-     * While [queue](#queue) passes only one task to one of a group of workers
-     * at a time, cargo passes an array of tasks to a single worker, repeating
-     * when the worker is finished.
-     *
-     * @name cargo
-     * @static
-     * @memberOf async
-     * @see async.queue
-     * @category Control Flow
-     * @param {Function} worker - An asynchronous function for processing an array
-     * of queued tasks, which must call its `callback(err)` argument when finished,
-     * with an optional `err` argument. Invoked with (tasks, callback).
-     * @param {number} [payload=Infinity] - An optional `integer` for determining
-     * how many tasks should be processed per round; if omitted, the default is
-     * unlimited.
-     * @returns {cargo} A cargo object to manage the tasks. Callbacks can
-     * attached as certain properties to listen for specific events during the
-     * lifecycle of the cargo and inner queue.
-     * @example
-     *
-     * // create a cargo object with payload 2
-     * var cargo = async.cargo(function(tasks, callback) {
-     *     for (var i=0; i<tasks.length; i++) {
-     *         console.log('hello ' + tasks[i].name);
-     *     }
-     *     callback();
-     * }, 2);
-     *
-     * // add some items
-     * cargo.push({name: 'foo'}, function(err) {
-     *     console.log('finished processing foo');
-     * });
-     * cargo.push({name: 'bar'}, function(err) {
-     *     console.log('finished processing bar');
-     * });
-     * cargo.push({name: 'baz'}, function(err) {
-     *     console.log('finished processing baz');
-     * });
-     */
-    function cargo(worker, payload) {
-      return queue(worker, 1, payload);
-    }
-
-    /**
-     * The same as `eachOf` but runs a maximum of `limit` async operations at a
-     * time.
-     *
-     * @name eachOfLimit
-     * @static
-     * @memberOf async
-     * @see async.eachOf
-     * @alias forEachOfLimit
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A function to apply to each
-     * item in `coll`. The `key` is the item's key, or index in the case of an
-     * array. The iteratee is passed a `callback(err)` which must be called once it
-     * has completed. If no error has occurred, the callback should be run without
-     * arguments or with an explicit `null` argument. Invoked with
-     * (item, key, callback).
-     * @param {Function} [callback] - A callback which is called when all
-     * `iteratee` functions have finished, or an error occurs. Invoked with (err).
-     */
-    function eachOfLimit(obj, limit, iteratee, cb) {
-      _eachOfLimit(limit)(obj, iteratee, cb);
-    }
-
-    /**
-     * The same as `eachOf` but runs only a single async operation at a time.
-     *
-     * @name eachOfSeries
-     * @static
-     * @memberOf async
-     * @see async.eachOf
-     * @alias forEachOfSeries
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each item in `coll`. The
-     * `key` is the item's key, or index in the case of an array. The iteratee is
-     * passed a `callback(err)` which must be called once it has completed. If no
-     * error has occurred, the callback should be run without arguments or with an
-     * explicit `null` argument. Invoked with (item, key, callback).
-     * @param {Function} [callback] - A callback which is called when all `iteratee`
-     * functions have finished, or an error occurs. Invoked with (err).
-     */
-    var eachOfSeries = doLimit(eachOfLimit, 1);
-
-    /**
-     * Reduces `coll` into a single value using an async `iteratee` to return each
-     * successive step. `memo` is the initial state of the reduction. This function
-     * only operates in series.
-     *
-     * For performance reasons, it may make sense to split a call to this function
-     * into a parallel map, and then use the normal `Array.prototype.reduce` on the
-     * results. This function is for situations where each step in the reduction
-     * needs to be async; if you can get the data before reducing it, then it's
-     * probably a good idea to do so.
-     *
-     * @name reduce
-     * @static
-     * @memberOf async
-     * @alias inject, foldl
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {*} memo - The initial state of the reduction.
-     * @param {Function} iteratee - A function applied to each item in the
-     * array to produce the next step in the reduction. The `iteratee` is passed a
-     * `callback(err, reduction)` which accepts an optional error as its first
-     * argument, and the state of the reduction as the second. If an error is
-     * passed to the callback, the reduction is stopped and the main `callback` is
-     * immediately called with the error. Invoked with (memo, item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Result is the reduced value. Invoked with
-     * (err, result).
-     * @example
-     *
-     * async.reduce([1,2,3], 0, function(memo, item, callback) {
-     *     // pointless async:
-     *     process.nextTick(function() {
-     *         callback(null, memo + item)
-     *     });
-     * }, function(err, result) {
-     *     // result is now equal to the last value of memo, which is 6
-     * });
-     */
-    function reduce(arr, memo, iteratee, cb) {
-        eachOfSeries(arr, function (x, i, cb) {
-            iteratee(memo, x, function (err, v) {
-                memo = v;
-                cb(err);
-            });
-        }, function (err) {
-            cb(err, memo);
-        });
-    }
-
-    /**
-     * Version of the compose function that is more natural to read. Each function
-     * consumes the return value of the previous function. It is the equivalent of
-     * {@link async.compose} with the arguments reversed.
-     *
-     * Each function is executed with the `this` binding of the composed function.
-     *
-     * @name seq
-     * @static
-     * @memberOf async
-     * @see async.compose
-     * @category Control Flow
-     * @param {...Function} functions - the asynchronous functions to compose
-     * @example
-     *
-     * // Requires lodash (or underscore), express3 and dresende's orm2.
-     * // Part of an app, that fetches cats of the logged user.
-     * // This example uses `seq` function to avoid overnesting and error
-     * // handling clutter.
-     * app.get('/cats', function(request, response) {
-     *     var User = request.models.User;
-     *     async.seq(
-     *         _.bind(User.get, User),  // 'User.get' has signature (id, callback(err, data))
-     *         function(user, fn) {
-     *             user.getCats(fn);      // 'getCats' has signature (callback(err, data))
-     *         }
-     *     )(req.session.user_id, function (err, cats) {
-     *         if (err) {
-     *             console.error(err);
-     *             response.json({ status: 'error', message: err.message });
-     *         } else {
-     *             response.json({ status: 'ok', message: 'Cats found', data: cats });
-     *         }
-     *     });
-     * });
-     */
-    function seq() /* functions... */{
-        var fns = arguments;
-        return rest(function (args) {
-            var that = this;
-
-            var cb = args[args.length - 1];
-            if (typeof cb == 'function') {
-                args.pop();
-            } else {
-                cb = noop;
-            }
-
-            reduce(fns, args, function (newargs, fn, cb) {
-                fn.apply(that, newargs.concat([rest(function (err, nextargs) {
-                    cb(err, nextargs);
-                })]));
-            }, function (err, results) {
-                cb.apply(that, [err].concat(results));
-            });
-        });
-    }
-
-    var reverse = Array.prototype.reverse;
-
-    /**
-     * Creates a function which is a composition of the passed asynchronous
-     * functions. Each function consumes the return value of the function that
-     * follows. Composing functions `f()`, `g()`, and `h()` would produce the result
-     * of `f(g(h()))`, only this version uses callbacks to obtain the return values.
-     *
-     * Each function is executed with the `this` binding of the composed function.
-     *
-     * @name compose
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {...Function} functions - the asynchronous functions to compose
-     * @example
-     *
-     * function add1(n, callback) {
-     *     setTimeout(function () {
-     *         callback(null, n + 1);
-     *     }, 10);
-     * }
-     *
-     * function mul3(n, callback) {
-     *     setTimeout(function () {
-     *         callback(null, n * 3);
-     *     }, 10);
-     * }
-     *
-     * var add1mul3 = async.compose(mul3, add1);
-     * add1mul3(4, function (err, result) {
-     *     // result now equals 15
-     * });
-     */
-    function compose() /* functions... */{
-      return seq.apply(null, reverse.call(arguments));
-    }
-
-    function concat$1(eachfn, arr, fn, callback) {
-        var result = [];
-        eachfn(arr, function (x, index, cb) {
-            fn(x, function (err, y) {
-                result = result.concat(y || []);
-                cb(err);
-            });
-        }, function (err) {
-            callback(err, result);
-        });
-    }
-
-    /**
-     * Like `each`, except that it passes the key (or index) as the second argument
-     * to the iteratee.
-     *
-     * @name eachOf
-     * @static
-     * @memberOf async
-     * @alias forEachOf
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each
-     * item in `coll`. The `key` is the item's key, or index in the case of an
-     * array. The iteratee is passed a `callback(err)` which must be called once it
-     * has completed. If no error has occurred, the callback should be run without
-     * arguments or with an explicit `null` argument. Invoked with
-     * (item, key, callback).
-     * @param {Function} [callback] - A callback which is called when all
-     * `iteratee` functions have finished, or an error occurs. Invoked with (err).
-     * @example
-     *
-     * var obj = {dev: "/dev.json", test: "/test.json", prod: "/prod.json"};
-     * var configs = {};
-     *
-     * async.forEachOf(obj, function (value, key, callback) {
-     *     fs.readFile(__dirname + value, "utf8", function (err, data) {
-     *         if (err) return callback(err);
-     *         try {
-     *             configs[key] = JSON.parse(data);
-     *         } catch (e) {
-     *             return callback(e);
-     *         }
-     *         callback();
-     *     });
-     * }, function (err) {
-     *     if (err) console.error(err.message);
-     *     // configs is now a map of JSON data
-     *     doSomethingWith(configs);
-     * });
-     */
-    var eachOf = doLimit(eachOfLimit, Infinity);
-
-    function doParallel(fn) {
-        return function (obj, iteratee, callback) {
-            return fn(eachOf, obj, iteratee, callback);
-        };
-    }
-
-    /**
-     * Applies `iteratee` to each item in `coll`, concatenating the results. Returns
-     * the concatenated list. The `iteratee`s are called in parallel, and the
-     * results are concatenated as they return. There is no guarantee that the
-     * results array will be returned in the original order of `coll` passed to the
-     * `iteratee` function.
-     *
-     * @name concat
-     * @static
-     * @memberOf async
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, results)` which must be called once
-     * it has completed with an error (which can be `null`) and an array of results.
-     * Invoked with (item, callback).
-     * @param {Function} [callback(err)] - A callback which is called after all the
-     * `iteratee` functions have finished, or an error occurs. Results is an array
-     * containing the concatenated results of the `iteratee` function. Invoked with
-     * (err, results).
-     * @example
-     *
-     * async.concat(['dir1','dir2','dir3'], fs.readdir, function(err, files) {
-     *     // files is now a list of filenames that exist in the 3 directories
-     * });
-     */
-    var concat = doParallel(concat$1);
-
-    function doSeries(fn) {
-        return function (obj, iteratee, callback) {
-            return fn(eachOfSeries, obj, iteratee, callback);
-        };
-    }
-
-    /**
-     * The same as `concat` but runs only a single async operation at a time.
-     *
-     * @name concatSeries
-     * @static
-     * @memberOf async
-     * @see async.concat
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, results)` which must be called once
-     * it has completed with an error (which can be `null`) and an array of results.
-     * Invoked with (item, callback).
-     * @param {Function} [callback(err)] - A callback which is called after all the
-     * `iteratee` functions have finished, or an error occurs. Results is an array
-     * containing the concatenated results of the `iteratee` function. Invoked with
-     * (err, results).
-     */
-    var concatSeries = doSeries(concat$1);
-
-    /**
-     * Returns a function that when called, calls-back with the values provided.
-     * Useful as the first function in a `waterfall`, or for plugging values in to
-     * `auto`.
-     *
-     * @name constant
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {...*} arguments... - Any number of arguments to automatically invoke
-     * callback with.
-     * @returns {Function} Returns a function that when invoked, automatically
-     * invokes the callback with the previous given arguments.
-     * @example
-     *
-     * async.waterfall([
-     *     async.constant(42),
-     *     function (value, next) {
-     *         // value === 42
-     *     },
-     *     //...
-     * ], callback);
-     *
-     * async.waterfall([
-     *     async.constant(filename, "utf8"),
-     *     fs.readFile,
-     *     function (fileData, next) {
-     *         //...
-     *     }
-     *     //...
-     * ], callback);
-     *
-     * async.auto({
-     *     hostname: async.constant("https://server.net/"),
-     *     port: findFreePort,
-     *     launchServer: ["hostname", "port", function (options, cb) {
-     *         startServer(options, cb);
-     *     }],
-     *     //...
-     * }, callback);
-     */
-    var constant = rest(function (values) {
-        var args = [null].concat(values);
-        return initialParams(function (ignoredArgs, callback) {
-            return callback.apply(this, args);
-        });
-    });
-
-    function _createTester(eachfn, check, getResult) {
-        return function (arr, limit, iteratee, cb) {
-            function done(err) {
-                if (cb) {
-                    if (err) {
-                        cb(err);
-                    } else {
-                        cb(null, getResult(false));
-                    }
-                }
-            }
-            function wrappedIteratee(x, _, callback) {
-                if (!cb) return callback();
-                iteratee(x, function (err, v) {
-                    if (cb) {
-                        if (err) {
-                            cb(err);
-                            cb = iteratee = false;
-                        } else if (check(v)) {
-                            cb(null, getResult(true, x));
-                            cb = iteratee = false;
-                        }
-                    }
-                    callback();
-                });
-            }
-            if (arguments.length > 3) {
-                cb = cb || noop;
-                eachfn(arr, limit, wrappedIteratee, done);
-            } else {
-                cb = iteratee;
-                cb = cb || noop;
-                iteratee = limit;
-                eachfn(arr, wrappedIteratee, done);
-            }
-        };
-    }
-
-    function _findGetResult(v, x) {
-        return x;
-    }
-
-    /**
-     * Returns the first value in `coll` that passes an async truth test. The
-     * `iteratee` is applied in parallel, meaning the first iteratee to return
-     * `true` will fire the detect `callback` with that result. That means the
-     * result might not be the first item in the original `coll` (in terms of order)
-     * that passes the test.
-
-     * If order within the original `coll` is important, then look at
-     * `detectSeries`.
-     *
-     * @name detect
-     * @static
-     * @memberOf async
-     * @alias find
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, truthValue)` which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called as soon as any
-     * iteratee returns `true`, or after all the `iteratee` functions have finished.
-     * Result will be the first item in the array that passes the truth test
-     * (iteratee) or the value `undefined` if none passed. Invoked with
-     * (err, result).
-     * @example
-     *
-     * async.detect(['file1','file2','file3'], function(filePath, callback) {
-     *     fs.access(filePath, function(err) {
-     *         callback(null, !err)
-     *     });
-     * }, function(err, result) {
-     *     // result now equals the first file in the list that exists
-     * });
-     */
-    var detect = _createTester(eachOf, identity, _findGetResult);
-
-    /**
-     * The same as `detect` but runs a maximum of `limit` async operations at a
-     * time.
-     *
-     * @name detectLimit
-     * @static
-     * @memberOf async
-     * @see async.detect
-     * @alias findLimit
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, truthValue)` which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called as soon as any
-     * iteratee returns `true`, or after all the `iteratee` functions have finished.
-     * Result will be the first item in the array that passes the truth test
-     * (iteratee) or the value `undefined` if none passed. Invoked with
-     * (err, result).
-     */
-    var detectLimit = _createTester(eachOfLimit, identity, _findGetResult);
-
-    /**
-     * The same as `detect` but runs only a single async operation at a time.
-     *
-     * @name detectSeries
-     * @static
-     * @memberOf async
-     * @see async.detect
-     * @alias findSeries
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, truthValue)` which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called as soon as any
-     * iteratee returns `true`, or after all the `iteratee` functions have finished.
-     * Result will be the first item in the array that passes the truth test
-     * (iteratee) or the value `undefined` if none passed. Invoked with
-     * (err, result).
-     */
-    var detectSeries = _createTester(eachOfSeries, identity, _findGetResult);
-
-    function consoleFunc(name) {
-        return rest(function (fn, args) {
-            fn.apply(null, args.concat([rest(function (err, args) {
-                if (typeof console === 'object') {
-                    if (err) {
-                        if (console.error) {
-                            console.error(err);
-                        }
-                    } else if (console[name]) {
-                        arrayEach(args, function (x) {
-                            console[name](x);
-                        });
-                    }
-                }
-            })]));
-        });
-    }
-
-    /**
-     * Logs the result of an `async` function to the `console` using `console.dir`
-     * to display the properties of the resulting object. Only works in Node.js or
-     * in browsers that support `console.dir` and `console.error` (such as FF and
-     * Chrome). If multiple arguments are returned from the async function,
-     * `console.dir` is called on each argument in order.
-     *
-     * @name log
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {Function} function - The function you want to eventually apply all
-     * arguments to.
-     * @param {...*} arguments... - Any number of arguments to apply to the function.
-     * @example
-     *
-     * // in a module
-     * var hello = function(name, callback) {
-     *     setTimeout(function() {
-     *         callback(null, {hello: name});
-     *     }, 1000);
-     * };
-     *
-     * // in the node repl
-     * node> async.dir(hello, 'world');
-     * {hello: 'world'}
-     */
-    var dir = consoleFunc('dir');
-
-    /**
-     * Like {@link async.whilst}, except the `test` is an asynchronous function that
-     * is passed a callback in the form of `function (err, truth)`. If error is
-     * passed to `test` or `fn`, the main callback is immediately called with the
-     * value of the error.
-     *
-     * @name during
-     * @static
-     * @memberOf async
-     * @see async.whilst
-     * @category Control Flow
-     * @param {Function} test - asynchronous truth test to perform before each
-     * execution of `fn`. Invoked with (callback).
-     * @param {Function} fn - A function which is called each time `test` passes.
-     * The function is passed a `callback(err)`, which must be called once it has
-     * completed with an optional `err` argument. Invoked with (callback).
-     * @param {Function} [callback] - A callback which is called after the test
-     * function has failed and repeated execution of `fn` has stopped. `callback`
-     * will be passed an error and any arguments passed to the final `fn`'s
-     * callback. Invoked with (err, [results]);
-     * @example
-     *
-     * var count = 0;
-     *
-     * async.during(
-     *     function (callback) {
-     *         return callback(null, count < 5);
-     *     },
-     *     function (callback) {
-     *         count++;
-     *         setTimeout(callback, 1000);
-     *     },
-     *     function (err) {
-     *         // 5 seconds have passed
-     *     }
-     * );
-     */
-    function during(test, iteratee, cb) {
-        cb = cb || noop;
-
-        var next = rest(function (err, args) {
-            if (err) {
-                cb(err);
-            } else {
-                args.push(check);
-                test.apply(this, args);
-            }
-        });
-
-        var check = function (err, truth) {
-            if (err) return cb(err);
-            if (!truth) return cb(null);
-            iteratee(next);
-        };
-
-        test(check);
-    }
-
-    /**
-     * The post-check version of {@link async.during}. To reflect the difference in
-     * the order of operations, the arguments `test` and `fn` are switched.
-     *
-     * Also a version of {@link async.doWhilst} with asynchronous `test` function.
-     * @name doDuring
-     * @static
-     * @memberOf async
-     * @see async.during
-     * @category Control Flow
-     * @param {Function} fn - A function which is called each time `test` passes.
-     * The function is passed a `callback(err)`, which must be called once it has
-     * completed with an optional `err` argument. Invoked with (callback).
-     * @param {Function} test - asynchronous truth test to perform before each
-     * execution of `fn`. Invoked with (callback).
-     * @param {Function} [callback] - A callback which is called after the test
-     * function has failed and repeated execution of `fn` has stopped. `callback`
-     * will be passed an error and any arguments passed to the final `fn`'s
-     * callback. Invoked with (err, [results]);
-     */
-    function doDuring(iteratee, test, cb) {
-        var calls = 0;
-
-        during(function (next) {
-            if (calls++ < 1) return next(null, true);
-            test.apply(this, arguments);
-        }, iteratee, cb);
-    }
-
-    /**
-     * Repeatedly call `fn`, while `test` returns `true`. Calls `callback` when
-     * stopped, or an error occurs.
-     *
-     * @name whilst
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Function} test - synchronous truth test to perform before each
-     * execution of `fn`. Invoked with ().
-     * @param {Function} fn - A function which is called each time `test` passes.
-     * The function is passed a `callback(err)`, which must be called once it has
-     * completed with an optional `err` argument. Invoked with (callback).
-     * @param {Function} [callback] - A callback which is called after the test
-     * function has failed and repeated execution of `fn` has stopped. `callback`
-     * will be passed an error and any arguments passed to the final `fn`'s
-     * callback. Invoked with (err, [results]);
-     * @example
-     *
-     * var count = 0;
-     * async.whilst(
-     *     function() { return count < 5; },
-     *     function(callback) {
-     *         count++;
-     *         setTimeout(function() {
-     *             callback(null, count);
-     *         }, 1000);
-     *     },
-     *     function (err, n) {
-     *         // 5 seconds have passed, n = 5
-     *     }
-     * );
-     */
-    function whilst(test, iteratee, cb) {
-        cb = cb || noop;
-        if (!test()) return cb(null);
-        var next = rest(function (err, args) {
-            if (err) return cb(err);
-            if (test.apply(this, args)) return iteratee(next);
-            cb.apply(null, [null].concat(args));
-        });
-        iteratee(next);
-    }
-
-    /**
-     * The post-check version of {@link async.whilst}. To reflect the difference in
-     * the order of operations, the arguments `test` and `fn` are switched.
-     *
-     * `doWhilst` is to `whilst` as `do while` is to `while` in plain JavaScript.
-     *
-     * @name doWhilst
-     * @static
-     * @memberOf async
-     * @see async.whilst
-     * @category Control Flow
-     * @param {Function} fn - A function which is called each time `test` passes.
-     * The function is passed a `callback(err)`, which must be called once it has
-     * completed with an optional `err` argument. Invoked with (callback).
-     * @param {Function} test - synchronous truth test to perform after each
-     * execution of `fn`. Invoked with Invoked with the non-error callback results
-     * of `fn`.
-     * @param {Function} [callback] - A callback which is called after the test
-     * function has failed and repeated execution of `fn` has stopped. `callback`
-     * will be passed an error and any arguments passed to the final `fn`'s
-     * callback. Invoked with (err, [results]);
-     */
-    function doWhilst(iteratee, test, cb) {
-        var calls = 0;
-        return whilst(function () {
-            return ++calls <= 1 || test.apply(this, arguments);
-        }, iteratee, cb);
-    }
-
-    /**
-     * Like {@link async.doWhilst}, except the `test` is inverted. Note the
-     * argument ordering differs from `until`.
-     *
-     * @name doUntil
-     * @static
-     * @memberOf async
-     * @see async.doWhilst
-     * @category Control Flow
-     * @param {Function} fn - A function which is called each time `test` fails.
-     * The function is passed a `callback(err)`, which must be called once it has
-     * completed with an optional `err` argument. Invoked with (callback).
-     * @param {Function} test - synchronous truth test to perform after each
-     * execution of `fn`. Invoked with the non-error callback results of `fn`.
-     * @param {Function} [callback] - A callback which is called after the test
-     * function has passed and repeated execution of `fn` has stopped. `callback`
-     * will be passed an error and any arguments passed to the final `fn`'s
-     * callback. Invoked with (err, [results]);
-     */
-    function doUntil(iteratee, test, cb) {
-        return doWhilst(iteratee, function () {
-            return !test.apply(this, arguments);
-        }, cb);
-    }
-
-    function _withoutIndex(iteratee) {
-        return function (value, index, callback) {
-            return iteratee(value, callback);
-        };
-    }
-
-    /**
-     * The same as `each` but runs a maximum of `limit` async operations at a time.
-     *
-     * @name eachLimit
-     * @static
-     * @memberOf async
-     * @see async.each
-     * @alias forEachLimit
-     * @category Collection
-     * @param {Array|Object} coll - A colleciton to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A function to apply to each item in `coll`. The
-     * iteratee is passed a `callback(err)` which must be called once it has
-     * completed. If no error has occurred, the `callback` should be run without
-     * arguments or with an explicit `null` argument. The array index is not passed
-     * to the iteratee. Invoked with (item, callback). If you need the index, use
-     * `eachOfLimit`.
-     * @param {Function} [callback] - A callback which is called when all
-     * `iteratee` functions have finished, or an error occurs. Invoked with (err).
-     */
-    function eachLimit(arr, limit, iteratee, cb) {
-      return _eachOfLimit(limit)(arr, _withoutIndex(iteratee), cb);
-    }
-
-    /**
-     * Applies the function `iteratee` to each item in `coll`, in parallel.
-     * The `iteratee` is called with an item from the list, and a callback for when
-     * it has finished. If the `iteratee` passes an error to its `callback`, the
-     * main `callback` (for the `each` function) is immediately called with the
-     * error.
-     *
-     * Note, that since this function applies `iteratee` to each item in parallel,
-     * there is no guarantee that the iteratee functions will complete in order.
-     *
-     * @name each
-     * @static
-     * @memberOf async
-     * @alias forEach
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each item
-     * in `coll`. The iteratee is passed a `callback(err)` which must be called once
-     * it has completed. If no error has occurred, the `callback` should be run
-     * without arguments or with an explicit `null` argument. The array index is not
-     * passed to the iteratee. Invoked with (item, callback). If you need the index,
-     * use `eachOf`.
-     * @param {Function} [callback] - A callback which is called when all
-     * `iteratee` functions have finished, or an error occurs. Invoked with (err).
-     * @example
-     *
-     * // assuming openFiles is an array of file names and saveFile is a function
-     * // to save the modified contents of that file:
-     *
-     * async.each(openFiles, saveFile, function(err){
-     *   // if any of the saves produced an error, err would equal that error
-     * });
-     *
-     * // assuming openFiles is an array of file names
-     * async.each(openFiles, function(file, callback) {
-     *
-     *     // Perform operation on file here.
-     *     console.log('Processing file ' + file);
-     *
-     *     if( file.length > 32 ) {
-     *       console.log('This file name is too long');
-     *       callback('File name too long');
-     *     } else {
-     *       // Do work to process file here
-     *       console.log('File processed');
-     *       callback();
-     *     }
-     * }, function(err) {
-     *     // if any of the file processing produced an error, err would equal that error
-     *     if( err ) {
-     *       // One of the iterations produced an error.
-     *       // All processing will now stop.
-     *       console.log('A file failed to process');
-     *     } else {
-     *       console.log('All files have been processed successfully');
-     *     }
-     * });
-     */
-    var each = doLimit(eachLimit, Infinity);
-
-    /**
-     * The same as `each` but runs only a single async operation at a time.
-     *
-     * @name eachSeries
-     * @static
-     * @memberOf async
-     * @see async.each
-     * @alias forEachSeries
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each
-     * item in `coll`. The iteratee is passed a `callback(err)` which must be called
-     * once it has completed. If no error has occurred, the `callback` should be run
-     * without arguments or with an explicit `null` argument. The array index is
-     * not passed to the iteratee. Invoked with (item, callback). If you need the
-     * index, use `eachOfSeries`.
-     * @param {Function} [callback] - A callback which is called when all
-     * `iteratee` functions have finished, or an error occurs. Invoked with (err).
-     */
-    var eachSeries = doLimit(eachLimit, 1);
-
-    /**
-     * Wrap an async function and ensure it calls its callback on a later tick of
-     * the event loop.  If the function already calls its callback on a next tick,
-     * no extra deferral is added. This is useful for preventing stack overflows
-     * (`RangeError: Maximum call stack size exceeded`) and generally keeping
-     * [Zalgo](http://blog.izs.me/post/59142742143/designing-apis-for-asynchrony)
-     * contained.
-     *
-     * @name ensureAsync
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {Function} fn - an async function, one that expects a node-style
-     * callback as its last argument.
-     * @returns {Function} Returns a wrapped function with the exact same call
-     * signature as the function passed in.
-     * @example
-     *
-     * function sometimesAsync(arg, callback) {
-     *     if (cache[arg]) {
-     *         return callback(null, cache[arg]); // this would be synchronous!!
-     *     } else {
-     *         doSomeIO(arg, callback); // this IO would be asynchronous
-     *     }
-     * }
-     *
-     * // this has a risk of stack overflows if many results are cached in a row
-     * async.mapSeries(args, sometimesAsync, done);
-     *
-     * // this will defer sometimesAsync's callback if necessary,
-     * // preventing stack overflows
-     * async.mapSeries(args, async.ensureAsync(sometimesAsync), done);
-     */
-    function ensureAsync(fn) {
-        return initialParams(function (args, callback) {
-            var sync = true;
-            args.push(function () {
-                var innerArgs = arguments;
-                if (sync) {
-                    setImmediate$1(function () {
-                        callback.apply(null, innerArgs);
-                    });
-                } else {
-                    callback.apply(null, innerArgs);
-                }
-            });
-            fn.apply(this, args);
-            sync = false;
-        });
-    }
-
-    function notId(v) {
-        return !v;
-    }
-
-    /**
-     * The same as `every` but runs a maximum of `limit` async operations at a time.
-     *
-     * @name everyLimit
-     * @static
-     * @memberOf async
-     * @see async.every
-     * @alias allLimit
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A truth test to apply to each item in the
-     * collection in parallel. The iteratee is passed a `callback(err, truthValue)`
-     * which must be called with a  boolean argument once it has completed. Invoked
-     * with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Result will be either `true` or `false`
-     * depending on the values of the async tests. Invoked with (err, result).
-     */
-    var everyLimit = _createTester(eachOfLimit, notId, notId);
-
-    /**
-     * Returns `true` if every element in `coll` satisfies an async test. If any
-     * iteratee call returns `false`, the main `callback` is immediately called.
-     *
-     * @name every
-     * @static
-     * @memberOf async
-     * @alias all
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in the
-     * collection in parallel. The iteratee is passed a `callback(err, truthValue)`
-     * which must be called with a  boolean argument once it has completed. Invoked
-     * with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Result will be either `true` or `false`
-     * depending on the values of the async tests. Invoked with (err, result).
-     * @example
-     *
-     * async.every(['file1','file2','file3'], function(filePath, callback) {
-     *     fs.access(filePath, function(err) {
-     *         callback(null, !err)
-     *     });
-     * }, function(err, result) {
-     *     // if result is true then every file exists
-     * });
-     */
-    var every = doLimit(everyLimit, Infinity);
-
-    /**
-     * The same as `every` but runs only a single async operation at a time.
-     *
-     * @name everySeries
-     * @static
-     * @memberOf async
-     * @see async.every
-     * @alias allSeries
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in the
-     * collection in parallel. The iteratee is passed a `callback(err, truthValue)`
-     * which must be called with a  boolean argument once it has completed. Invoked
-     * with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Result will be either `true` or `false`
-     * depending on the values of the async tests. Invoked with (err, result).
-     */
-    var everySeries = doLimit(everyLimit, 1);
-
-    function _filter(eachfn, arr, iteratee, callback) {
-        var results = [];
-        eachfn(arr, function (x, index, callback) {
-            iteratee(x, function (err, v) {
-                if (err) {
-                    callback(err);
-                } else {
-                    if (v) {
-                        results.push({ index: index, value: x });
-                    }
-                    callback();
-                }
-            });
-        }, function (err) {
-            if (err) {
-                callback(err);
-            } else {
-                callback(null, arrayMap(results.sort(function (a, b) {
-                    return a.index - b.index;
-                }), baseProperty('value')));
-            }
-        });
-    }
-
-    /**
-     * The same as `filter` but runs a maximum of `limit` async operations at a
-     * time.
-     *
-     * @name filterLimit
-     * @static
-     * @memberOf async
-     * @see async.filter
-     * @alias selectLimit
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Invoked with (err, results).
-     */
-    var filterLimit = doParallelLimit(_filter);
-
-    /**
-     * Returns a new array of all the values in `coll` which pass an async truth
-     * test. This operation is performed in parallel, but the results array will be
-     * in the same order as the original.
-     *
-     * @name filter
-     * @static
-     * @memberOf async
-     * @alias select
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Invoked with (err, results).
-     * @example
-     *
-     * async.filter(['file1','file2','file3'], function(filePath, callback) {
-     *     fs.access(filePath, function(err) {
-     *         callback(null, !err)
-     *     });
-     * }, function(err, results) {
-     *     // results now equals an array of the existing files
-     * });
-     */
-    var filter = doLimit(filterLimit, Infinity);
-
-    /**
-     * The same as `filter` but runs only a single async operation at a time.
-     *
-     * @name filterSeries
-     * @static
-     * @memberOf async
-     * @see async.filter
-     * @alias selectSeries
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Invoked with (err, results)
-     */
-    var filterSeries = doLimit(filterLimit, 1);
-
-    /**
-     * Calls the asynchronous function `fn` with a callback parameter that allows it
-     * to call itself again, in series, indefinitely.
-
-     * If an error is passed to the
-     * callback then `errback` is called with the error, and execution stops,
-     * otherwise it will never be called.
-     *
-     * @name forever
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Function} fn - a function to call repeatedly. Invoked with (next).
-     * @param {Function} [errback] - when `fn` passes an error to it's callback,
-     * this function will be called, and execution stops. Invoked with (err).
-     * @example
-     *
-     * async.forever(
-     *     function(next) {
-     *         // next is suitable for passing to things that need a callback(err [, whatever]);
-     *         // it will result in this function being called again.
-     *     },
-     *     function(err) {
-     *         // if next is called with a value in its first parameter, it will appear
-     *         // in here as 'err', and execution will stop.
-     *     }
-     * );
-     */
-    function forever(fn, cb) {
-        var done = onlyOnce(cb || noop);
-        var task = ensureAsync(fn);
-
-        function next(err) {
-            if (err) return done(err);
-            task(next);
-        }
-        next();
-    }
-
-    /**
-     * Creates an iterator function which calls the next function in the `tasks`
-     * array, returning a continuation to call the next one after that. It's also
-     * possible to “peek” at the next iterator with `iterator.next()`.
-     *
-     * This function is used internally by the `async` module, but can be useful
-     * when you want to manually control the flow of functions in series.
-     *
-     * @name iterator
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Array} tasks - An array of functions to run.
-     * @returns The next function to run in the series.
-     * @example
-     *
-     * var iterator = async.iterator([
-     *     function() { sys.p('one'); },
-     *     function() { sys.p('two'); },
-     *     function() { sys.p('three'); }
-     * ]);
-     *
-     * node> var iterator2 = iterator();
-     * 'one'
-     * node> var iterator3 = iterator2();
-     * 'two'
-     * node> iterator3();
-     * 'three'
-     * node> var nextfn = iterator2.next();
-     * node> nextfn();
-     * 'three'
-     */
-    function iterator$1 (tasks) {
-        function makeCallback(index) {
-            function fn() {
-                if (tasks.length) {
-                    tasks[index].apply(null, arguments);
-                }
-                return fn.next();
-            }
-            fn.next = function () {
-                return index < tasks.length - 1 ? makeCallback(index + 1) : null;
-            };
-            return fn;
-        }
-        return makeCallback(0);
-    }
-
-    /**
-     * Logs the result of an `async` function to the `console`. Only works in
-     * Node.js or in browsers that support `console.log` and `console.error` (such
-     * as FF and Chrome). If multiple arguments are returned from the async
-     * function, `console.log` is called on each argument in order.
-     *
-     * @name log
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {Function} function - The function you want to eventually apply all
-     * arguments to.
-     * @param {...*} arguments... - Any number of arguments to apply to the function.
-     * @example
-     *
-     * // in a module
-     * var hello = function(name, callback) {
-     *     setTimeout(function() {
-     *         callback(null, 'hello ' + name);
-     *     }, 1000);
-     * };
-     *
-     * // in the node repl
-     * node> async.log(hello, 'world');
-     * 'hello world'
-     */
-    var log = consoleFunc('log');
-
-    /**
-     * The same as `mapValues` but runs a maximum of `limit` async operations at a
-     * time.
-     *
-     * @name mapValuesLimit
-     * @static
-     * @memberOf async
-     * @see async.mapValues
-     * @category Collection
-     * @param {Object} obj - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A function to apply to each value in `obj`.
-     * The iteratee is passed a `callback(err, transformed)` which must be called
-     * once it has completed with an error (which can be `null`) and a
-     * transformed value. Invoked with (value, key, callback).
-     * @param {Function} [callback] - A callback which is called when all `iteratee`
-     * functions have finished, or an error occurs. Result is an object of the
-     * transformed values from the `obj`. Invoked with (err, result).
-     */
-    function mapValuesLimit(obj, limit, iteratee, callback) {
-        var newObj = {};
-        eachOfLimit(obj, limit, function (val, key, next) {
-            iteratee(val, key, function (err, result) {
-                if (err) return next(err);
-                newObj[key] = result;
-                next();
-            });
-        }, function (err) {
-            callback(err, newObj);
-        });
-    }
-
-    /**
-     * A relative of `map`, designed for use with objects.
-     *
-     * Produces a new Object by mapping each value of `obj` through the `iteratee`
-     * function. The `iteratee` is called each `value` and `key` from `obj` and a
-     * callback for when it has finished processing. Each of these callbacks takes
-     * two arguments: an `error`, and the transformed item from `obj`. If `iteratee`
-     * passes an error to its callback, the main `callback` (for the `mapValues`
-     * function) is immediately called with the error.
-     *
-     * Note, the order of the keys in the result is not guaranteed.  The keys will
-     * be roughly in the order they complete, (but this is very engine-specific)
-     *
-     * @name mapValues
-     * @static
-     * @memberOf async
-     * @category Collection
-     * @param {Object} obj - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each value and key in
-     * `coll`. The iteratee is passed a `callback(err, transformed)` which must be
-     * called once it has completed with an error (which can be `null`) and a
-     * transformed value. Invoked with (value, key, callback).
-     * @param {Function} [callback] - A callback which is called when all `iteratee`
-     * functions have finished, or an error occurs. Results is an array of the
-     * transformed items from the `obj`. Invoked with (err, result).
-     * @example
-     *
-     * async.mapValues({
-     *     f1: 'file1',
-     *     f2: 'file2',
-     *     f3: 'file3'
-     * }, fs.stat, function(err, result) {
-     *     // results is now a map of stats for each file, e.g.
-     *     // {
-     *     //     f1: [stats for file1],
-     *     //     f2: [stats for file2],
-     *     //     f3: [stats for file3]
-     *     // }
-     * });
-     */
-
-    var mapValues = doLimit(mapValuesLimit, Infinity);
-
-    /**
-     * The same as `mapValues` but runs only a single async operation at a time.
-     *
-     * @name mapValuesSeries
-     * @static
-     * @memberOf async
-     * @see async.mapValues
-     * @category Collection
-     * @param {Object} obj - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each value in `obj`.
-     * The iteratee is passed a `callback(err, transformed)` which must be called
-     * once it has completed with an error (which can be `null`) and a
-     * transformed value. Invoked with (value, key, callback).
-     * @param {Function} [callback] - A callback which is called when all `iteratee`
-     * functions have finished, or an error occurs. Result is an object of the
-     * transformed values from the `obj`. Invoked with (err, result).
-     */
-    var mapValuesSeries = doLimit(mapValuesLimit, 1);
-
-    function has(obj, key) {
-        return key in obj;
-    }
-
-    /**
-     * Caches the results of an `async` function. When creating a hash to store
-     * function results against, the callback is omitted from the hash and an
-     * optional hash function can be used.
-     *
-     * If no hash function is specified, the first argument is used as a hash key,
-     * which may work reasonably if it is a string or a data type that converts to a
-     * distinct string. Note that objects and arrays will not behave reasonably.
-     * Neither will cases where the other arguments are significant. In such cases,
-     * specify your own hash function.
-     *
-     * The cache of results is exposed as the `memo` property of the function
-     * returned by `memoize`.
-     *
-     * @name memoize
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {Function} fn - The function to proxy and cache results from.
-     * @param {Function} hasher - An optional function for generating a custom hash
-     * for storing results. It has all the arguments applied to it apart from the
-     * callback, and must be synchronous.
-     * @example
-     *
-     * var slow_fn = function(name, callback) {
-     *     // do something
-     *     callback(null, result);
-     * };
-     * var fn = async.memoize(slow_fn);
-     *
-     * // fn can now be used as if it were slow_fn
-     * fn('some name', function() {
-     *     // callback
-     * });
-     */
-    function memoize$1(fn, hasher) {
-        var memo = Object.create(null);
-        var queues = Object.create(null);
-        hasher = hasher || identity;
-        var memoized = initialParams(function memoized(args, callback) {
-            var key = hasher.apply(null, args);
-            if (has(memo, key)) {
-                setImmediate$1(function () {
-                    callback.apply(null, memo[key]);
-                });
-            } else if (has(queues, key)) {
-                queues[key].push(callback);
-            } else {
-                queues[key] = [callback];
-                fn.apply(null, args.concat([rest(function (args) {
-                    memo[key] = args;
-                    var q = queues[key];
-                    delete queues[key];
-                    for (var i = 0, l = q.length; i < l; i++) {
-                        q[i].apply(null, args);
-                    }
-                })]));
-            }
-        });
-        memoized.memo = memo;
-        memoized.unmemoized = fn;
-        return memoized;
-    }
-
-    /**
-     * Calls `callback` on a later loop around the event loop. In Node.js this just
-     * calls `setImmediate`.  In the browser it will use `setImmediate` if
-     * available, otherwise `setTimeout(callback, 0)`, which means other higher
-     * priority events may precede the execution of `callback`.
-     *
-     * This is used internally for browser-compatibility purposes.
-     *
-     * @name nextTick
-     * @static
-     * @memberOf async
-     * @alias setImmediate
-     * @category Util
-     * @param {Function} callback - The function to call on a later loop around
-     * the event loop. Invoked with (args...).
-     * @param {...*} args... - any number of additional arguments to pass to the
-     * callback on the next tick.
-     * @example
-     *
-     * var call_order = [];
-     * async.nextTick(function() {
-     *     call_order.push('two');
-     *     // call_order now equals ['one','two']
-     * });
-     * call_order.push('one');
-     *
-     * async.setImmediate(function (a, b, c) {
-     *     // a, b, and c equal 1, 2, and 3
-     * }, 1, 2, 3);
-     */
-    var _defer$1;
-
-    if (hasNextTick) {
-        _defer$1 = process.nextTick;
-    } else if (hasSetImmediate) {
-        _defer$1 = setImmediate;
-    } else {
-        _defer$1 = fallback;
-    }
-
-    var nextTick = wrap(_defer$1);
-
-    function _parallel(eachfn, tasks, callback) {
-        callback = callback || noop;
-        var results = isArrayLike(tasks) ? [] : {};
-
-        eachfn(tasks, function (task, key, callback) {
-            task(rest(function (err, args) {
-                if (args.length <= 1) {
-                    args = args[0];
-                }
-                results[key] = args;
-                callback(err);
-            }));
-        }, function (err) {
-            callback(err, results);
-        });
-    }
-
-    /**
-     * The same as `parallel` but runs a maximum of `limit` async operations at a
-     * time.
-     *
-     * @name parallel
-     * @static
-     * @memberOf async
-     * @see async.parallel
-     * @category Control Flow
-     * @param {Array|Collection} tasks - A collection containing functions to run.
-     * Each function is passed a `callback(err, result)` which it must call on
-     * completion with an error `err` (which can be `null`) and an optional `result`
-     * value.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} [callback] - An optional callback to run once all the
-     * functions have completed successfully. This function gets a results array
-     * (or object) containing all the result arguments passed to the task callbacks.
-     * Invoked with (err, results).
-     */
-    function parallelLimit(tasks, limit, cb) {
-      return _parallel(_eachOfLimit(limit), tasks, cb);
-    }
-
-    /**
-     * Run the `tasks` collection of functions in parallel, without waiting until
-     * the previous function has completed. If any of the functions pass an error to
-     * its callback, the main `callback` is immediately called with the value of the
-     * error. Once the `tasks` have completed, the results are passed to the final
-     * `callback` as an array.
-     *
-     * **Note:** `parallel` is about kicking-off I/O tasks in parallel, not about
-     * parallel execution of code.  If your tasks do not use any timers or perform
-     * any I/O, they will actually be executed in series.  Any synchronous setup
-     * sections for each task will happen one after the other.  JavaScript remains
-     * single-threaded.
-     *
-     * It is also possible to use an object instead of an array. Each property will
-     * be run as a function and the results will be passed to the final `callback`
-     * as an object instead of an array. This can be a more readable way of handling
-     * results from {@link async.parallel}.
-     *
-     * @name parallel
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Array|Object} tasks - A collection containing functions to run.
-     * Each function is passed a `callback(err, result)` which it must call on
-     * completion with an error `err` (which can be `null`) and an optional `result`
-     * value.
-     * @param {Function} [callback] - An optional callback to run once all the
-     * functions have completed successfully. This function gets a results array
-     * (or object) containing all the result arguments passed to the task callbacks.
-     * Invoked with (err, results).
-     * @example
-     * async.parallel([
-     *     function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 'one');
-     *         }, 200);
-     *     },
-     *     function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 'two');
-     *         }, 100);
-     *     }
-     * ],
-     * // optional callback
-     * function(err, results) {
-     *     // the results array will equal ['one','two'] even though
-     *     // the second function had a shorter timeout.
-     * });
-     *
-     * // an example using an object instead of an array
-     * async.parallel({
-     *     one: function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 1);
-     *         }, 200);
-     *     },
-     *     two: function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 2);
-     *         }, 100);
-     *     }
-     * }, function(err, results) {
-     *     // results is now equals to: {one: 1, two: 2}
-     * });
-     */
-    var parallel = doLimit(parallelLimit, Infinity);
-
-    /**
-     * A queue of tasks for the worker function to complete.
-     * @typedef {Object} queue
-     * @property {Function} length - a function returning the number of items
-     * waiting to be processed. Invoke with ().
-     * @property {Function} started - a function returning whether or not any
-     * items have been pushed and processed by the queue. Invoke with ().
-     * @property {Function} running - a function returning the number of items
-     * currently being processed. Invoke with ().
-     * @property {Function} workersList - a function returning the array of items
-     * currently being processed. Invoke with ().
-     * @property {Function} idle - a function returning false if there are items
-     * waiting or being processed, or true if not. Invoke with ().
-     * @property {number} concurrency - an integer for determining how many `worker`
-     * functions should be run in parallel. This property can be changed after a
-     * `queue` is created to alter the concurrency on-the-fly.
-     * @property {Function} push - add a new task to the `queue`. Calls `callback`
-     * once the `worker` has finished processing the task. Instead of a single task,
-     * a `tasks` array can be submitted. The respective callback is used for every
-     * task in the list. Invoke with (task, [callback]),
-     * @property {Function} unshift - add a new task to the front of the `queue`.
-     * Invoke with (task, [callback]).
-     * @property {Function} saturated - a callback that is called when the number of
-     * running workers hits the `concurrency` limit, and further tasks will be
-     * queued.
-     * @property {Function} unsaturated - a callback that is called when the number
-     * of running workers is less than the `concurrency` & `buffer` limits, and
-     * further tasks will not be queued.
-     * @property {number} buffer - A minimum threshold buffer in order to say that
-     * the `queue` is `unsaturated`.
-     * @property {Function} empty - a callback that is called when the last item
-     * from the `queue` is given to a `worker`.
-     * @property {Function} drain - a callback that is called when the last item
-     * from the `queue` has returned from the `worker`.
-     * @property {Function} error - a callback that is called when a task errors.
-     * Has the signature `function(error, task)`.
-     * @property {boolean} paused - a boolean for determining whether the queue is
-     * in a paused state.
-     * @property {Function} pause - a function that pauses the processing of tasks
-     * until `resume()` is called. Invoke with ().
-     * @property {Function} resume - a function that resumes the processing of
-     * queued tasks when the queue is paused. Invoke with ().
-     * @property {Function} kill - a function that removes the `drain` callback and
-     * empties remaining tasks from the queue forcing it to go idle. Invoke with ().
-     */
-
-    /**
-     * Creates a `queue` object with the specified `concurrency`. Tasks added to the
-     * `queue` are processed in parallel (up to the `concurrency` limit). If all
-     * `worker`s are in progress, the task is queued until one becomes available.
-     * Once a `worker` completes a `task`, that `task`'s callback is called.
-     *
-     * @name queue
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Function} worker - An asynchronous function for processing a queued
-     * task, which must call its `callback(err)` argument when finished, with an
-     * optional `error` as an argument.  If you want to handle errors from an
-     * individual task, pass a callback to `q.push()`. Invoked with
-     * (task, callback).
-     * @param {number} [concurrency=1] - An `integer` for determining how many
-     * `worker` functions should be run in parallel.  If omitted, the concurrency
-     * defaults to `1`.  If the concurrency is `0`, an error is thrown.
-     * @returns {queue} A queue object to manage the tasks. Callbacks can
-     * attached as certain properties to listen for specific events during the
-     * lifecycle of the queue.
-     * @example
-     *
-     * // create a queue object with concurrency 2
-     * var q = async.queue(function(task, callback) {
-     *     console.log('hello ' + task.name);
-     *     callback();
-     * }, 2);
-     *
-     * // assign a callback
-     * q.drain = function() {
-     *     console.log('all items have been processed');
-     * };
-     *
-     * // add some items to the queue
-     * q.push({name: 'foo'}, function(err) {
-     *     console.log('finished processing foo');
-     * });
-     * q.push({name: 'bar'}, function (err) {
-     *     console.log('finished processing bar');
-     * });
-     *
-     * // add some items to the queue (batch-wise)
-     * q.push([{name: 'baz'},{name: 'bay'},{name: 'bax'}], function(err) {
-     *     console.log('finished processing item');
-     * });
-     *
-     * // add some items to the front of the queue
-     * q.unshift({name: 'bar'}, function (err) {
-     *     console.log('finished processing bar');
-     * });
-     */
-    function queue$1 (worker, concurrency) {
-      return queue(function (items, cb) {
-        worker(items[0], cb);
-      }, concurrency, 1);
-    }
-
-    /**
-     * The same as {@link async.queue} only tasks are assigned a priority and
-     * completed in ascending priority order.
-     *
-     * @name priorityQueue
-     * @static
-     * @memberOf async
-     * @see async.queue
-     * @category Control Flow
-     * @param {Function} worker - An asynchronous function for processing a queued
-     * task, which must call its `callback(err)` argument when finished, with an
-     * optional `error` as an argument.  If you want to handle errors from an
-     * individual task, pass a callback to `q.push()`. Invoked with
-     * (task, callback).
-     * @param {number} concurrency - An `integer` for determining how many `worker`
-     * functions should be run in parallel.  If omitted, the concurrency defaults to
-     * `1`.  If the concurrency is `0`, an error is thrown.
-     * @returns {queue} A priorityQueue object to manage the tasks. There are two
-     * differences between `queue` and `priorityQueue` objects:
-     * * `push(task, priority, [callback])` - `priority` should be a number. If an
-     *   array of `tasks` is given, all tasks will be assigned the same priority.
-     * * The `unshift` method was removed.
-     */
-    function priorityQueue (worker, concurrency) {
-        function _compareTasks(a, b) {
-            return a.priority - b.priority;
-        }
-
-        function _binarySearch(sequence, item, compare) {
-            var beg = -1,
-                end = sequence.length - 1;
-            while (beg < end) {
-                var mid = beg + (end - beg + 1 >>> 1);
-                if (compare(item, sequence[mid]) >= 0) {
-                    beg = mid;
-                } else {
-                    end = mid - 1;
-                }
-            }
-            return beg;
-        }
-
-        function _insert(q, data, priority, callback) {
-            if (callback != null && typeof callback !== 'function') {
-                throw new Error('task callback must be a function');
-            }
-            q.started = true;
-            if (!isArray(data)) {
-                data = [data];
-            }
-            if (data.length === 0) {
-                // call drain immediately if there are no tasks
-                return setImmediate$1(function () {
-                    q.drain();
-                });
-            }
-            arrayEach(data, function (task) {
-                var item = {
-                    data: task,
-                    priority: priority,
-                    callback: typeof callback === 'function' ? callback : noop
-                };
-
-                q.tasks.splice(_binarySearch(q.tasks, item, _compareTasks) + 1, 0, item);
-
-                setImmediate$1(q.process);
-            });
-        }
-
-        // Start with a normal queue
-        var q = queue$1(worker, concurrency);
 
-        // Override push to accept second parameter representing priority
-        q.push = function (data, priority, callback) {
-            _insert(q, data, priority, callback);
-        };
-
-        // Remove unshift function
-        delete q.unshift;
-
-        return q;
-    }
-
-    /**
-     * Creates a `baseEach` or `baseEachRight` function.
-     *
-     * @private
-     * @param {Function} eachFunc The function to iterate over a collection.
-     * @param {boolean} [fromRight] Specify iterating from right to left.
-     * @returns {Function} Returns the new base function.
-     */
-    function createBaseEach(eachFunc, fromRight) {
-      return function(collection, iteratee) {
-        if (collection == null) {
-          return collection;
-        }
-        if (!isArrayLike(collection)) {
-          return eachFunc(collection, iteratee);
-        }
-        var length = collection.length,
-            index = fromRight ? length : -1,
-            iterable = Object(collection);
-
-        while ((fromRight ? index-- : ++index < length)) {
-          if (iteratee(iterable[index], index, iterable) === false) {
-            break;
+      function timeoutCallback() {
+          var name = asyncFn.name || 'anonymous';
+          var error = new Error('Callback function "' + name + '" timed out.');
+          error.code = 'ETIMEDOUT';
+          if (info) {
+              error.info = info;
           }
-        }
-        return collection;
-      };
-    }
-
-    /**
-     * The base implementation of `_.forEach` without support for iteratee shorthands.
-     *
-     * @private
-     * @param {Array|Object} collection The collection to iterate over.
-     * @param {Function} iteratee The function invoked per iteration.
-     * @returns {Array|Object} Returns `collection`.
-     */
-    var baseEach = createBaseEach(baseForOwn);
-
-    /**
-     * Iterates over elements of `collection` and invokes `iteratee` for each element.
-     * The iteratee is invoked with three arguments: (value, index|key, collection).
-     * Iteratee functions may exit iteration early by explicitly returning `false`.
-     *
-     * **Note:** As with other "Collections" methods, objects with a "length"
-     * property are iterated like arrays. To avoid this behavior use `_.forIn`
-     * or `_.forOwn` for object iteration.
-     *
-     * @static
-     * @memberOf _
-     * @since 0.1.0
-     * @alias each
-     * @category Collection
-     * @param {Array|Object} collection The collection to iterate over.
-     * @param {Function} [iteratee=_.identity] The function invoked per iteration.
-     * @returns {Array|Object} Returns `collection`.
-     * @see _.forEachRight
-     * @example
-     *
-     * _([1, 2]).forEach(function(value) {
-     *   console.log(value);
-     * });
-     * // => Logs `1` then `2`.
-     *
-     * _.forEach({ 'a': 1, 'b': 2 }, function(value, key) {
-     *   console.log(key);
-     * });
-     * // => Logs 'a' then 'b' (iteration order is not guaranteed).
-     */
-    function forEach(collection, iteratee) {
-      var func = isArray(collection) ? arrayEach : baseEach;
-      return func(collection, baseIteratee(iteratee, 3));
-    }
-
-    /**
-     * Runs the `tasks` array of functions in parallel, without waiting until the
-     * previous function has completed. Once any the `tasks` completed or pass an
-     * error to its callback, the main `callback` is immediately called. It's
-     * equivalent to `Promise.race()`.
-     *
-     * @name race
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Array} tasks - An array containing functions to run. Each function
-     * is passed a `callback(err, result)` which it must call on completion with an
-     * error `err` (which can be `null`) and an optional `result` value.
-     * @param {Function} callback - A callback to run once any of the functions have
-     * completed. This function gets an error or result from the first function that
-     * completed. Invoked with (err, result).
-     * @example
-     *
-     * async.race([
-     *     function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 'one');
-     *         }, 200);
-     *     },
-     *     function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 'two');
-     *         }, 100);
-     *     }
-     * ],
-     * // main callback
-     * function(err, result) {
-     *     // the result will be equal to 'two' as it finishes earlier
-     * });
-     */
-    function race(tasks, cb) {
-        cb = once(cb || noop);
-        if (!isArray(tasks)) return cb(new TypeError('First argument to race must be an array of functions'));
-        if (!tasks.length) return cb();
-        forEach(tasks, function (task) {
-            task(cb);
-        });
-    }
-
-    var slice = Array.prototype.slice;
-
-    /**
-     * Same as `reduce`, only operates on `coll` in reverse order.
-     *
-     * @name reduceRight
-     * @static
-     * @memberOf async
-     * @see async.reduce
-     * @alias foldr
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {*} memo - The initial state of the reduction.
-     * @param {Function} iteratee - A function applied to each item in the
-     * array to produce the next step in the reduction. The `iteratee` is passed a
-     * `callback(err, reduction)` which accepts an optional error as its first
-     * argument, and the state of the reduction as the second. If an error is
-     * passed to the callback, the reduction is stopped and the main `callback` is
-     * immediately called with the error. Invoked with (memo, item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Result is the reduced value. Invoked with
-     * (err, result).
-     */
-    function reduceRight(arr, memo, iteratee, cb) {
-      var reversed = slice.call(arr).reverse();
-      reduce(reversed, memo, iteratee, cb);
-    }
-
-    /**
-     * Wraps the function in another function that always returns data even when it
-     * errors.
-     *
-     * The object returned has either the property `error` or `value`.
-     *
-     * @name reflect
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {Function} function - The function you want to wrap
-     * @returns {Function} - A function that always passes null to it's callback as
-     * the error. The second argument to the callback will be an `object` with
-     * either an `error` or a `value` property.
-     * @example
-     *
-     * async.parallel([
-     *     async.reflect(function(callback) {
-     *         // do some stuff ...
-     *         callback(null, 'one');
-     *     }),
-     *     async.reflect(function(callback) {
-     *         // do some more stuff but error ...
-     *         callback('bad stuff happened');
-     *     }),
-     *     async.reflect(function(callback) {
-     *         // do some more stuff ...
-     *         callback(null, 'two');
-     *     })
-     * ],
-     * // optional callback
-     * function(err, results) {
-     *     // values
-     *     // results[0].value = 'one'
-     *     // results[1].error = 'bad stuff happened'
-     *     // results[2].value = 'two'
-     * });
-     */
-    function reflect(fn) {
-        return initialParams(function reflectOn(args, reflectCallback) {
-            args.push(rest(function callback(err, cbArgs) {
-                if (err) {
-                    reflectCallback(null, {
-                        error: err
-                    });
-                } else {
-                    var value = null;
-                    if (cbArgs.length === 1) {
-                        value = cbArgs[0];
-                    } else if (cbArgs.length > 1) {
-                        value = cbArgs;
-                    }
-                    reflectCallback(null, {
-                        value: value
-                    });
-                }
-            }));
-
-            return fn.apply(this, args);
-        });
-    }
-
-    function reject$1(eachfn, arr, iteratee, callback) {
-        _filter(eachfn, arr, function (value, cb) {
-            iteratee(value, function (err, v) {
-                if (err) {
-                    cb(err);
-                } else {
-                    cb(null, !v);
-                }
-            });
-        }, callback);
-    }
-
-    /**
-     * The same as `reject` but runs a maximum of `limit` async operations at a
-     * time.
-     *
-     * @name rejectLimit
-     * @static
-     * @memberOf async
-     * @see async.reject
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Invoked with (err, results).
-     */
-    var rejectLimit = doParallelLimit(reject$1);
-
-    /**
-     * The opposite of `filter`. Removes values that pass an `async` truth test.
-     *
-     * @name reject
-     * @static
-     * @memberOf async
-     * @see async.filter
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Invoked with (err, results).
-     * @example
-     *
-     * async.reject(['file1','file2','file3'], function(filePath, callback) {
-     *     fs.access(filePath, function(err) {
-     *         callback(null, !err)
-     *     });
-     * }, function(err, results) {
-     *     // results now equals an array of missing files
-     *     createFiles(results);
-     * });
-     */
-    var reject = doLimit(rejectLimit, Infinity);
-
-    /**
-     * A helper function that wraps an array of functions with reflect.
-     *
-     * @name reflectAll
-     * @static
-     * @memberOf async
-     * @see async.reflect
-     * @category Util
-     * @param {Array} tasks - The array of functions to wrap in `async.reflect`.
-     * @returns {Array} Returns an array of functions, each function wrapped in
-     * `async.reflect`
-     * @example
-     *
-     * let tasks = [
-     *     function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 'one');
-     *         }, 200);
-     *     },
-     *     function(callback) {
-     *         // do some more stuff but error ...
-     *         callback(new Error('bad stuff happened'));
-     *     },
-     *     function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 'two');
-     *         }, 100);
-     *     }
-     * ];
-     *
-     * async.parallel(async.reflectAll(tasks),
-     * // optional callback
-     * function(err, results) {
-     *     // values
-     *     // results[0].value = 'one'
-     *     // results[1].error = Error('bad stuff happened')
-     *     // results[2].value = 'two'
-     * });
-     */
-    function reflectAll(tasks) {
-      return tasks.map(reflect);
-    }
+          timedOut = true;
+          originalCallback(error);
+      }
 
-    /**
-     * The same as `reject` but runs only a single async operation at a time.
-     *
-     * @name rejectSeries
-     * @static
-     * @memberOf async
-     * @see async.reject
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in `coll`.
-     * The `iteratee` is passed a `callback(err, truthValue)`, which must be called
-     * with a boolean argument once it has completed. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Invoked with (err, results).
-     */
-    var rejectSeries = doLimit(rejectLimit, 1);
-
-    /**
-     * Run the functions in the `tasks` collection in series, each one running once
-     * the previous function has completed. If any functions in the series pass an
-     * error to its callback, no more functions are run, and `callback` is
-     * immediately called with the value of the error. Otherwise, `callback`
-     * receives an array of results when `tasks` have completed.
-     *
-     * It is also possible to use an object instead of an array. Each property will
-     * be run as a function, and the results will be passed to the final `callback`
-     * as an object instead of an array. This can be a more readable way of handling
-     *  results from {@link async.series}.
-     *
-     * **Note** that while many implementations preserve the order of object
-     * properties, the [ECMAScript Language Specification](http://www.ecma-international.org/ecma-262/5.1/#sec-8.6)
-     * explicitly states that
-     *
-     * > The mechanics and order of enumerating the properties is not specified.
-     *
-     * So if you rely on the order in which your series of functions are executed,
-     * and want this to work on all platforms, consider using an array.
-     *
-     * @name series
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Array|Object} tasks - A collection containing functions to run, each
-     * function is passed a `callback(err, result)` it must call on completion with
-     * an error `err` (which can be `null`) and an optional `result` value.
-     * @param {Function} [callback] - An optional callback to run once all the
-     * functions have completed. This function gets a results array (or object)
-     * containing all the result arguments passed to the `task` callbacks. Invoked
-     * with (err, result).
-     * @example
-     * async.series([
-     *     function(callback) {
-     *         // do some stuff ...
-     *         callback(null, 'one');
-     *     },
-     *     function(callback) {
-     *         // do some more stuff ...
-     *         callback(null, 'two');
-     *     }
-     * ],
-     * // optional callback
-     * function(err, results) {
-     *     // results is now equal to ['one', 'two']
-     * });
-     *
-     * async.series({
-     *     one: function(callback) {
-     *         setTimeout(function() {
-     *             callback(null, 1);
-     *         }, 200);
-     *     },
-     *     two: function(callback){
-     *         setTimeout(function() {
-     *             callback(null, 2);
-     *         }, 100);
-     *     }
-     * }, function(err, results) {
-     *     // results is now equal to: {one: 1, two: 2}
-     * });
-     */
-    function series(tasks, cb) {
-      return _parallel(eachOfSeries, tasks, cb);
-    }
+      return initialParams(function (args, origCallback) {
+          originalCallback = origCallback;
+          // setup timer and call original function
+          timer = setTimeout(timeoutCallback, milliseconds);
+          asyncFn.apply(null, args.concat(injectedCallback));
+      });
+  }
+
+  /* Built-in method references for those with the same name as other `lodash` methods. */
+  var nativeCeil = Math.ceil;
+  var nativeMax$1 = Math.max;
+  /**
+   * The base implementation of `_.range` and `_.rangeRight` which doesn't
+   * coerce arguments to numbers.
+   *
+   * @private
+   * @param {number} start The start of the range.
+   * @param {number} end The end of the range.
+   * @param {number} step The value to increment or decrement by.
+   * @param {boolean} [fromRight] Specify iterating from right to left.
+   * @returns {Array} Returns the range of numbers.
+   */
+  function baseRange(start, end, step, fromRight) {
+    var index = -1,
+        length = nativeMax$1(nativeCeil((end - start) / (step || 1)), 0),
+        result = Array(length);
+
+    while (length--) {
+      result[fromRight ? length : ++index] = start;
+      start += step;
+    }
+    return result;
+  }
+
+  /**
+   * The same as [times]{@link module:ControlFlow.times} but runs a maximum of `limit` async operations at a
+   * time.
+   *
+   * @name timesLimit
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.times]{@link module:ControlFlow.times}
+   * @category Control Flow
+   * @param {number} count - The number of times to run the function.
+   * @param {number} limit - The maximum number of async operations at a time.
+   * @param {Function} iteratee - The function to call `n` times. Invoked with the
+   * iteration index and a callback (n, next).
+   * @param {Function} callback - see [async.map]{@link module:Collections.map}.
+   */
+  function timeLimit(count, limit, iteratee, callback) {
+    mapLimit(baseRange(0, count, 1), limit, iteratee, callback);
+  }
+
+  /**
+   * Calls the `iteratee` function `n` times, and accumulates results in the same
+   * manner you would use with [map]{@link module:Collections.map}.
+   *
+   * @name times
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.map]{@link module:Collections.map}
+   * @category Control Flow
+   * @param {number} n - The number of times to run the function.
+   * @param {Function} iteratee - The function to call `n` times. Invoked with the
+   * iteration index and a callback (n, next).
+   * @param {Function} callback - see {@link module:Collections.map}.
+   * @example
+   *
+   * // Pretend this is some complicated async factory
+   * var createUser = function(id, callback) {
+   *     callback(null, {
+   *         id: 'user' + id
+   *     });
+   * };
+   *
+   * // generate 5 users
+   * async.times(5, function(n, next) {
+   *     createUser(n, function(err, user) {
+   *         next(err, user);
+   *     });
+   * }, function(err, users) {
+   *     // we should now have 5 users
+   * });
+   */
+  var times = doLimit(timeLimit, Infinity);
+
+  /**
+   * The same as [times]{@link module:ControlFlow.times} but runs only a single async operation at a time.
+   *
+   * @name timesSeries
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.times]{@link module:ControlFlow.times}
+   * @category Control Flow
+   * @param {number} n - The number of times to run the function.
+   * @param {Function} iteratee - The function to call `n` times. Invoked with the
+   * iteration index and a callback (n, next).
+   * @param {Function} callback - see {@link module:Collections.map}.
+   */
+  var timesSeries = doLimit(timeLimit, 1);
+
+  /**
+   * A relative of `reduce`.  Takes an Object or Array, and iterates over each
+   * element in series, each step potentially mutating an `accumulator` value.
+   * The type of the accumulator defaults to the type of collection passed in.
+   *
+   * @name transform
+   * @static
+   * @memberOf module:Collections
+   * @method
+   * @category Collection
+   * @param {Array|Object} coll - A collection to iterate over.
+   * @param {*} [accumulator] - The initial state of the transform.  If omitted,
+   * it will default to an empty Object or Array, depending on the type of `coll`
+   * @param {Function} iteratee - A function applied to each item in the
+   * collection that potentially modifies the accumulator. The `iteratee` is
+   * passed a `callback(err)` which accepts an optional error as its first
+   * argument. If an error is passed to the callback, the transform is stopped
+   * and the main `callback` is immediately called with the error.
+   * Invoked with (accumulator, item, key, callback).
+   * @param {Function} [callback] - A callback which is called after all the
+   * `iteratee` functions have finished. Result is the transformed accumulator.
+   * Invoked with (err, result).
+   * @example
+   *
+   * async.transform([1,2,3], function(acc, item, index, callback) {
+   *     // pointless async:
+   *     process.nextTick(function() {
+   *         acc.push(item * 2)
+   *         callback(null)
+   *     });
+   * }, function(err, result) {
+   *     // result is now equal to [2, 4, 6]
+   * });
+   *
+   * @example
+   *
+   * async.transform({a: 1, b: 2, c: 3}, function (obj, val, key, callback) {
+   *     setImmediate(function () {
+   *         obj[key] = val * 2;
+   *         callback();
+   *     })
+   * }, function (err, result) {
+   *     // result is equal to {a: 2, b: 4, c: 6}
+   * })
+   */
+  function transform(coll, accumulator, iteratee, callback) {
+      if (arguments.length === 3) {
+          callback = iteratee;
+          iteratee = accumulator;
+          accumulator = isArray(coll) ? [] : {};
+      }
 
-    /**
-     * Creates a function that returns `value`.
-     *
-     * @static
-     * @memberOf _
-     * @since 2.4.0
-     * @category Util
-     * @param {*} value The value to return from the new function.
-     * @returns {Function} Returns the new constant function.
-     * @example
-     *
-     * var objects = _.times(2, _.constant({ 'a': 1 }));
-     *
-     * console.log(objects);
-     * // => [{ 'a': 1 }, { 'a': 1 }]
-     *
-     * console.log(objects[0] === objects[1]);
-     * // => true
-     */
-    function constant$1(value) {
-      return function() {
-        return value;
+      eachOf(coll, function (v, k, cb) {
+          iteratee(accumulator, v, k, cb);
+      }, function (err) {
+          callback(err, accumulator);
+      });
+  }
+
+  /**
+   * Undoes a [memoize]{@link module:Utils.memoize}d function, reverting it to the original,
+   * unmemoized form. Handy for testing.
+   *
+   * @name unmemoize
+   * @static
+   * @memberOf module:Utils
+   * @method
+   * @see [async.memoize]{@link module:Utils.memoize}
+   * @category Util
+   * @param {Function} fn - the memoized function
+   * @returns {Function} a function that calls the original unmemoized function
+   */
+  function unmemoize(fn) {
+      return function () {
+          return (fn.unmemoized || fn).apply(null, arguments);
       };
-    }
-
-    /**
-     * Attempts to get a successful response from `task` no more than `times` times
-     * before returning an error. If the task is successful, the `callback` will be
-     * passed the result of the successful task. If all attempts fail, the callback
-     * will be passed the error and result (if any) of the final attempt.
-     *
-     * @name retry
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Object|number} [opts = {times: 5, interval: 0}| 5] - Can be either an
-     * object with `times` and `interval` or a number.
-     * * `times` - The number of attempts to make before giving up.  The default
-     *   is `5`.
-     * * `interval` - The time to wait between retries, in milliseconds.  The
-     *   default is `0`. The interval may also be specified as a function of the
-     *   retry count (see example).
-     * * If `opts` is a number, the number specifies the number of times to retry,
-     *   with the default interval of `0`.
-     * @param {Function} task - A function which receives two arguments: (1) a
-     * `callback(err, result)` which must be called when finished, passing `err`
-     * (which can be `null`) and the `result` of the function's execution, and (2)
-     * a `results` object, containing the results of the previously executed
-     * functions (if nested inside another control flow). Invoked with
-     * (callback, results).
-     * @param {Function} [callback] - An optional callback which is called when the
-     * task has succeeded, or after the final failed attempt. It receives the `err`
-     * and `result` arguments of the last attempt at completing the `task`. Invoked
-     * with (err, results).
-     * @example
-     *
-     * // The `retry` function can be used as a stand-alone control flow by passing
-     * // a callback, as shown below:
-     *
-     * // try calling apiMethod 3 times
-     * async.retry(3, apiMethod, function(err, result) {
-     *     // do something with the result
-     * });
-     *
-     * // try calling apiMethod 3 times, waiting 200 ms between each retry
-     * async.retry({times: 3, interval: 200}, apiMethod, function(err, result) {
-     *     // do something with the result
-     * });
-     *
-     * // try calling apiMethod 10 times with exponential backoff
-     * // (i.e. intervals of 100, 200, 400, 800, 1600, ... milliseconds)
-     * async.retry({
-     *   times: 10,
-     *   interval: function(retryCount) {
-     *     return 50 * Math.pow(2, retryCount);
-     *   }
-     * }, apiMethod, function(err, result) {
-     *     // do something with the result
-     * });
-     *
-     * // try calling apiMethod the default 5 times no delay between each retry
-     * async.retry(apiMethod, function(err, result) {
-     *     // do something with the result
-     * });
-     *
-     * // It can also be embedded within other control flow functions to retry
-     * // individual methods that are not as reliable, like this:
-     * async.auto({
-     *     users: api.getUsers.bind(api),
-     *     payments: async.retry(3, api.getPayments.bind(api))
-     * }, function(err, results) {
-     *     // do something with the results
-     * });
-     */
-    function retry(times, task, callback) {
-        var DEFAULT_TIMES = 5;
-        var DEFAULT_INTERVAL = 0;
-
-        var opts = {
-            times: DEFAULT_TIMES,
-            intervalFunc: constant$1(DEFAULT_INTERVAL)
-        };
-
-        function parseTimes(acc, t) {
-            if (typeof t === 'object') {
-                acc.times = +t.times || DEFAULT_TIMES;
-
-                acc.intervalFunc = typeof t.interval === 'function' ? t.interval : constant$1(+t.interval || DEFAULT_INTERVAL);
-            } else if (typeof t === 'number' || typeof t === 'string') {
-                acc.times = +t || DEFAULT_TIMES;
-            } else {
-                throw new Error("Invalid arguments for async.retry");
-            }
-        }
-
-        if (arguments.length < 3 && typeof times === 'function') {
-            callback = task || noop;
-            task = times;
-        } else {
-            parseTimes(opts, times);
-            callback = callback || noop;
-        }
-
-        if (typeof task !== 'function') {
-            throw new Error("Invalid arguments for async.retry");
-        }
-
-        var attempts = [];
-        for (var i = 1; i < opts.times + 1; i++) {
-            var isFinalAttempt = i == opts.times;
-            attempts.push(retryAttempt(isFinalAttempt));
-            var interval = opts.intervalFunc(i);
-            if (!isFinalAttempt && interval > 0) {
-                attempts.push(retryInterval(interval));
-            }
-        }
-
-        series(attempts, function (done, data) {
-            data = data[data.length - 1];
-            callback(data.err, data.result);
-        });
-
-        function retryAttempt(isFinalAttempt) {
-            return function (seriesCallback) {
-                task(function (err, result) {
-                    seriesCallback(!err || isFinalAttempt, {
-                        err: err,
-                        result: result
-                    });
-                });
-            };
-        }
-
-        function retryInterval(interval) {
-            return function (seriesCallback) {
-                setTimeout(function () {
-                    seriesCallback(null);
-                }, interval);
-            };
-        }
-    }
-
-    /**
-     * A close relative of `retry`.  This method wraps a task and makes it
-     * retryable, rather than immediately calling it with retries.
-     *
-     * @name retryable
-     * @static
-     * @memberOf async
-     * @see async.retry
-     * @category Control Flow
-     * @param {Object|number} [opts = {times: 5, interval: 0}| 5] - optional
-     * options, exactly the same as from `retry`
-     * @param {Function} task - the asynchronous function to wrap
-     * @returns {Functions} The wrapped function, which when invoked, will retry on
-     * an error, based on the parameters specified in `opts`.
-     * @example
-     *
-     * async.auto({
-     *     dep1: async.retryable(3, getFromFlakyService),
-     *     process: ["dep1", async.retryable(3, function (results, cb) {
-     *         maybeProcessData(results.dep1, cb);
-     *     })]
-     * }, callback);
-     */
-    function retryable (opts, task) {
-        if (!task) {
-            task = opts;
-            opts = null;
-        }
-        return initialParams(function (args, callback) {
-            function taskFn(cb) {
-                task.apply(null, args.concat([cb]));
-            }
-
-            if (opts) retry(opts, taskFn, callback);else retry(taskFn, callback);
-        });
-    }
-
-    /**
-     * The same as `some` but runs a maximum of `limit` async operations at a time.
-     *
-     * @name someLimit
-     * @static
-     * @memberOf async
-     * @see async.some
-     * @alias anyLimit
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - A truth test to apply to each item in the array
-     * in parallel. The iteratee is passed a `callback(err, truthValue)` which must
-     * be called with a boolean argument once it has completed. Invoked with
-     * (item, callback).
-     * @param {Function} [callback] - A callback which is called as soon as any
-     * iteratee returns `true`, or after all the iteratee functions have finished.
-     * Result will be either `true` or `false` depending on the values of the async
-     * tests. Invoked with (err, result).
-     */
-    var someLimit = _createTester(eachOfLimit, Boolean, identity);
-
-    /**
-     * Returns `true` if at least one element in the `coll` satisfies an async test.
-     * If any iteratee call returns `true`, the main `callback` is immediately
-     * called.
-     *
-     * @name some
-     * @static
-     * @memberOf async
-     * @alias any
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in the array
-     * in parallel. The iteratee is passed a `callback(err, truthValue)` which must
-     * be called with a boolean argument once it has completed. Invoked with
-     * (item, callback).
-     * @param {Function} [callback] - A callback which is called as soon as any
-     * iteratee returns `true`, or after all the iteratee functions have finished.
-     * Result will be either `true` or `false` depending on the values of the async
-     * tests. Invoked with (err, result).
-     * @example
-     *
-     * async.some(['file1','file2','file3'], function(filePath, callback) {
-     *     fs.access(filePath, function(err) {
-     *         callback(null, !err)
-     *     });
-     * }, function(err, result) {
-     *     // if result is true then at least one of the files exists
-     * });
-     */
-    var some = doLimit(someLimit, Infinity);
-
-    /**
-     * The same as `some` but runs only a single async operation at a time.
-     *
-     * @name someSeries
-     * @static
-     * @memberOf async
-     * @see async.some
-     * @alias anySeries
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A truth test to apply to each item in the array
-     * in parallel. The iteratee is passed a `callback(err, truthValue)` which must
-     * be called with a boolean argument once it has completed. Invoked with
-     * (item, callback).
-     * @param {Function} [callback] - A callback which is called as soon as any
-     * iteratee returns `true`, or after all the iteratee functions have finished.
-     * Result will be either `true` or `false` depending on the values of the async
-     * tests. Invoked with (err, result).
-     */
-    var someSeries = doLimit(someLimit, 1);
-
-    /**
-     * Sorts a list by the results of running each `coll` value through an async
-     * `iteratee`.
-     *
-     * @name sortBy
-     * @static
-     * @memberOf async
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {Function} iteratee - A function to apply to each item in `coll`.
-     * The iteratee is passed a `callback(err, sortValue)` which must be called once
-     * it has completed with an error (which can be `null`) and a value to use as
-     * the sort criteria. Invoked with (item, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished, or an error occurs. Results is the items
-     * from the original `coll` sorted by the values returned by the `iteratee`
-     * calls. Invoked with (err, results).
-     * @example
-     *
-     * async.sortBy(['file1','file2','file3'], function(file, callback) {
-     *     fs.stat(file, function(err, stats) {
-     *         callback(err, stats.mtime);
-     *     });
-     * }, function(err, results) {
-     *     // results is now the original array of files sorted by
-     *     // modified date
-     * });
-     *
-     * // By modifying the callback parameter the
-     * // sorting order can be influenced:
-     *
-     * // ascending order
-     * async.sortBy([1,9,3,5], function(x, callback) {
-     *     callback(null, x);
-     * }, function(err,result) {
-     *     // result callback
-     * });
-     *
-     * // descending order
-     * async.sortBy([1,9,3,5], function(x, callback) {
-     *     callback(null, x*-1);    //<- x*-1 instead of x, turns the order around
-     * }, function(err,result) {
-     *     // result callback
-     * });
-     */
-    function sortBy(arr, iteratee, cb) {
-        map(arr, function (x, cb) {
-            iteratee(x, function (err, criteria) {
-                if (err) return cb(err);
-                cb(null, { value: x, criteria: criteria });
-            });
-        }, function (err, results) {
-            if (err) return cb(err);
-            cb(null, arrayMap(results.sort(comparator), baseProperty('value')));
-        });
-
-        function comparator(left, right) {
-            var a = left.criteria,
-                b = right.criteria;
-            return a < b ? -1 : a > b ? 1 : 0;
-        }
-    }
-
-    /**
-     * Sets a time limit on an asynchronous function. If the function does not call
-     * its callback within the specified miliseconds, it will be called with a
-     * timeout error. The code property for the error object will be `'ETIMEDOUT'`.
-     *
-     * @name timeout
-     * @static
-     * @memberOf async
-     * @category Util
-     * @param {Function} function - The asynchronous function you want to set the
-     * time limit.
-     * @param {number} miliseconds - The specified time limit.
-     * @param {*} [info] - Any variable you want attached (`string`, `object`, etc)
-     * to timeout Error for more information..
-     * @returns {Function} Returns a wrapped function that can be used with any of
-     * the control flow functions.
-     * @example
-     *
-     * async.timeout(function(callback) {
-     *     doAsyncTask(callback);
-     * }, 1000);
-     */
-    function timeout(asyncFn, miliseconds, info) {
-        var originalCallback, timer;
-        var timedOut = false;
-
-        function injectedCallback() {
-            if (!timedOut) {
-                originalCallback.apply(null, arguments);
-                clearTimeout(timer);
-            }
-        }
-
-        function timeoutCallback() {
-            var name = asyncFn.name || 'anonymous';
-            var error = new Error('Callback function "' + name + '" timed out.');
-            error.code = 'ETIMEDOUT';
-            if (info) {
-                error.info = info;
-            }
-            timedOut = true;
-            originalCallback(error);
-        }
+  }
+
+  /**
+   * Repeatedly call `fn` until `test` returns `true`. Calls `callback` when
+   * stopped, or an error occurs. `callback` will be passed an error and any
+   * arguments passed to the final `fn`'s callback.
+   *
+   * The inverse of [whilst]{@link module:ControlFlow.whilst}.
+   *
+   * @name until
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @see [async.whilst]{@link module:ControlFlow.whilst}
+   * @category Control Flow
+   * @param {Function} test - synchronous truth test to perform before each
+   * execution of `fn`. Invoked with ().
+   * @param {Function} fn - A function which is called each time `test` fails.
+   * The function is passed a `callback(err)`, which must be called once it has
+   * completed with an optional `err` argument. Invoked with (callback).
+   * @param {Function} [callback] - A callback which is called after the test
+   * function has passed and repeated execution of `fn` has stopped. `callback`
+   * will be passed an error and any arguments passed to the final `fn`'s
+   * callback. Invoked with (err, [results]);
+   */
+  function until(test, fn, callback) {
+      whilst(function () {
+          return !test.apply(this, arguments);
+      }, fn, callback);
+  }
+
+  /**
+   * Runs the `tasks` array of functions in series, each passing their results to
+   * the next in the array. However, if any of the `tasks` pass an error to their
+   * own callback, the next function is not executed, and the main `callback` is
+   * immediately called with the error.
+   *
+   * @name waterfall
+   * @static
+   * @memberOf module:ControlFlow
+   * @method
+   * @category Control Flow
+   * @param {Array} tasks - An array of functions to run, each function is passed
+   * a `callback(err, result1, result2, ...)` it must call on completion. The
+   * first argument is an error (which can be `null`) and any further arguments
+   * will be passed as arguments in order to the next task.
+   * @param {Function} [callback] - An optional callback to run once all the
+   * functions have completed. This will be passed the results of the last task's
+   * callback. Invoked with (err, [results]).
+   * @returns undefined
+   * @example
+   *
+   * async.waterfall([
+   *     function(callback) {
+   *         callback(null, 'one', 'two');
+   *     },
+   *     function(arg1, arg2, callback) {
+   *         // arg1 now equals 'one' and arg2 now equals 'two'
+   *         callback(null, 'three');
+   *     },
+   *     function(arg1, callback) {
+   *         // arg1 now equals 'three'
+   *         callback(null, 'done');
+   *     }
+   * ], function (err, result) {
+   *     // result now equals 'done'
+   * });
+   *
+   * // Or, with named functions:
+   * async.waterfall([
+   *     myFirstFunction,
+   *     mySecondFunction,
+   *     myLastFunction,
+   * ], function (err, result) {
+   *     // result now equals 'done'
+   * });
+   * function myFirstFunction(callback) {
+   *     callback(null, 'one', 'two');
+   * }
+   * function mySecondFunction(arg1, arg2, callback) {
+   *     // arg1 now equals 'one' and arg2 now equals 'two'
+   *     callback(null, 'three');
+   * }
+   * function myLastFunction(arg1, callback) {
+   *     // arg1 now equals 'three'
+   *     callback(null, 'done');
+   * }
+   */
+  function waterfall (tasks, callback) {
+      callback = once(callback || noop);
+      if (!isArray(tasks)) return callback(new Error('First argument to waterfall must be an array of functions'));
+      if (!tasks.length) return callback();
+      var taskIndex = 0;
+
+      function nextTask(args) {
+          if (taskIndex === tasks.length) {
+              return callback.apply(null, [null].concat(args));
+          }
 
-        return initialParams(function (args, origCallback) {
-            originalCallback = origCallback;
-            // setup timer and call original function
-            timer = setTimeout(timeoutCallback, miliseconds);
-            asyncFn.apply(null, args.concat(injectedCallback));
-        });
-    }
+          var taskCallback = onlyOnce(rest(function (err, args) {
+              if (err) {
+                  return callback.apply(null, [err].concat(args));
+              }
+              nextTask(args);
+          }));
 
-    /* Built-in method references for those with the same name as other `lodash` methods. */
-    var nativeCeil = Math.ceil;
-    var nativeMax$1 = Math.max;
-    /**
-     * The base implementation of `_.range` and `_.rangeRight` which doesn't
-     * coerce arguments to numbers.
-     *
-     * @private
-     * @param {number} start The start of the range.
-     * @param {number} end The end of the range.
-     * @param {number} step The value to increment or decrement by.
-     * @param {boolean} [fromRight] Specify iterating from right to left.
-     * @returns {Array} Returns the range of numbers.
-     */
-    function baseRange(start, end, step, fromRight) {
-      var index = -1,
-          length = nativeMax$1(nativeCeil((end - start) / (step || 1)), 0),
-          result = Array(length);
+          args.push(taskCallback);
 
-      while (length--) {
-        result[fromRight ? length : ++index] = start;
-        start += step;
+          var task = tasks[taskIndex++];
+          task.apply(null, args);
       }
-      return result;
-    }
-
-    /**
-    * The same as {@link times} but runs a maximum of `limit` async operations at a
-    * time.
-     *
-     * @name timesLimit
-     * @static
-     * @memberOf async
-     * @see async.times
-     * @category Control Flow
-     * @param {number} n - The number of times to run the function.
-     * @param {number} limit - The maximum number of async operations at a time.
-     * @param {Function} iteratee - The function to call `n` times. Invoked with the
-     * iteration index and a callback (n, next).
-     * @param {Function} callback - see {@link async.map}.
-     */
-    function timeLimit(count, limit, iteratee, cb) {
-      return mapLimit(baseRange(0, count, 1), limit, iteratee, cb);
-    }
-
-    /**
-     * Calls the `iteratee` function `n` times, and accumulates results in the same
-     * manner you would use with {@link async.map}.
-     *
-     * @name times
-     * @static
-     * @memberOf async
-     * @see async.map
-     * @category Control Flow
-     * @param {number} n - The number of times to run the function.
-     * @param {Function} iteratee - The function to call `n` times. Invoked with the
-     * iteration index and a callback (n, next).
-     * @param {Function} callback - see {@link async.map}.
-     * @example
-     *
-     * // Pretend this is some complicated async factory
-     * var createUser = function(id, callback) {
-     *     callback(null, {
-     *         id: 'user' + id
-     *     });
-     * };
-     *
-     * // generate 5 users
-     * async.times(5, function(n, next) {
-     *     createUser(n, function(err, user) {
-     *         next(err, user);
-     *     });
-     * }, function(err, users) {
-     *     // we should now have 5 users
-     * });
-     */
-    var times = doLimit(timeLimit, Infinity);
-
-    /**
-     * The same as {@link async.times} but runs only a single async operation at a time.
-     *
-     * @name timesSeries
-     * @static
-     * @memberOf async
-     * @see async.times
-     * @category Control Flow
-     * @param {number} n - The number of times to run the function.
-     * @param {Function} iteratee - The function to call `n` times. Invoked with the
-     * iteration index and a callback (n, next).
-     * @param {Function} callback - see {@link async.map}.
-     */
-    var timesSeries = doLimit(timeLimit, 1);
-
-    /**
-     * A relative of `reduce`.  Takes an Object or Array, and iterates over each
-     * element in series, each step potentially mutating an `accumulator` value.
-     * The type of the accumulator defaults to the type of collection passed in.
-     *
-     * @name transform
-     * @static
-     * @memberOf async
-     * @category Collection
-     * @param {Array|Object} coll - A collection to iterate over.
-     * @param {*} [accumulator] - The initial state of the transform.  If omitted,
-     * it will default to an empty Object or Array, depending on the type of `coll`
-     * @param {Function} iteratee - A function applied to each item in the
-     * collection that potentially modifies the accumulator. The `iteratee` is
-     * passed a `callback(err)` which accepts an optional error as its first
-     * argument. If an error is passed to the callback, the transform is stopped
-     * and the main `callback` is immediately called with the error.
-     * Invoked with (accumulator, item, key, callback).
-     * @param {Function} [callback] - A callback which is called after all the
-     * `iteratee` functions have finished. Result is the transformed accumulator.
-     * Invoked with (err, result).
-     * @example
-     *
-     * async.transform([1,2,3], function(acc, item, index, callback) {
-     *     // pointless async:
-     *     process.nextTick(function() {
-     *         acc.push(item * 2)
-     *         callback(null)
-     *     });
-     * }, function(err, result) {
-     *     // result is now equal to [2, 4, 6]
-     * });
-     *
-     * @example
-     *
-     * async.transform({a: 1, b: 2, c: 3}, function (obj, val, key, callback) {
-     *     setImmediate(function () {
-     *         obj[key] = val * 2;
-     *         callback();
-     *     })
-     * }, function (err, result) {
-     *     // result is equal to {a: 2, b: 4, c: 6}
-     * })
-     */
-    function transform(arr, acc, iteratee, callback) {
-        if (arguments.length === 3) {
-            callback = iteratee;
-            iteratee = acc;
-            acc = isArray(arr) ? [] : {};
-        }
-
-        eachOf(arr, function (v, k, cb) {
-            iteratee(acc, v, k, cb);
-        }, function (err) {
-            callback(err, acc);
-        });
-    }
-
-    /**
-     * Undoes a {@link async.memoize}d function, reverting it to the original,
-     * unmemoized form. Handy for testing.
-     *
-     * @name unmemoize
-     * @static
-     * @memberOf async
-     * @see async.memoize
-     * @category Util
-     * @param {Function} fn - the memoized function
-     */
-    function unmemoize(fn) {
-        return function () {
-            return (fn.unmemoized || fn).apply(null, arguments);
-        };
-    }
-
-    /**
-     * Repeatedly call `fn` until `test` returns `true`. Calls `callback` when
-     * stopped, or an error occurs. `callback` will be passed an error and any
-     * arguments passed to the final `fn`'s callback.
-     *
-     * The inverse of {@link async.whilst}.
-     *
-     * @name until
-     * @static
-     * @memberOf async
-     * @see async.whilst
-     * @category Control Flow
-     * @param {Function} test - synchronous truth test to perform before each
-     * execution of `fn`. Invoked with ().
-     * @param {Function} fn - A function which is called each time `test` fails.
-     * The function is passed a `callback(err)`, which must be called once it has
-     * completed with an optional `err` argument. Invoked with (callback).
-     * @param {Function} [callback] - A callback which is called after the test
-     * function has passed and repeated execution of `fn` has stopped. `callback`
-     * will be passed an error and any arguments passed to the final `fn`'s
-     * callback. Invoked with (err, [results]);
-     */
-    function until(test, iteratee, cb) {
-        return whilst(function () {
-            return !test.apply(this, arguments);
-        }, iteratee, cb);
-    }
-
-    /**
-     * Runs the `tasks` array of functions in series, each passing their results to
-     * the next in the array. However, if any of the `tasks` pass an error to their
-     * own callback, the next function is not executed, and the main `callback` is
-     * immediately called with the error.
-     *
-     * @name waterfall
-     * @static
-     * @memberOf async
-     * @category Control Flow
-     * @param {Array} tasks - An array of functions to run, each function is passed
-     * a `callback(err, result1, result2, ...)` it must call on completion. The
-     * first argument is an error (which can be `null`) and any further arguments
-     * will be passed as arguments in order to the next task.
-     * @param {Function} [callback] - An optional callback to run once all the
-     * functions have completed. This will be passed the results of the last task's
-     * callback. Invoked with (err, [results]).
-     * @example
-     *
-     * async.waterfall([
-     *     function(callback) {
-     *         callback(null, 'one', 'two');
-     *     },
-     *     function(arg1, arg2, callback) {
-     *         // arg1 now equals 'one' and arg2 now equals 'two'
-     *         callback(null, 'three');
-     *     },
-     *     function(arg1, callback) {
-     *         // arg1 now equals 'three'
-     *         callback(null, 'done');
-     *     }
-     * ], function (err, result) {
-     *     // result now equals 'done'
-     * });
-     *
-     * // Or, with named functions:
-     * async.waterfall([
-     *     myFirstFunction,
-     *     mySecondFunction,
-     *     myLastFunction,
-     * ], function (err, result) {
-     *     // result now equals 'done'
-     * });
-     * function myFirstFunction(callback) {
-     *     callback(null, 'one', 'two');
-     * }
-     * function mySecondFunction(arg1, arg2, callback) {
-     *     // arg1 now equals 'one' and arg2 now equals 'two'
-     *     callback(null, 'three');
-     * }
-     * function myLastFunction(arg1, callback) {
-     *     // arg1 now equals 'three'
-     *     callback(null, 'done');
-     * }
-     */
-    function waterfall (tasks, cb) {
-        cb = once(cb || noop);
-        if (!isArray(tasks)) return cb(new Error('First argument to waterfall must be an array of functions'));
-        if (!tasks.length) return cb();
-        var taskIndex = 0;
-
-        function nextTask(args) {
-            if (taskIndex === tasks.length) {
-                return cb.apply(null, [null].concat(args));
-            }
-
-            var taskCallback = onlyOnce(rest(function (err, args) {
-                if (err) {
-                    return cb.apply(null, [err].concat(args));
-                }
-                nextTask(args);
-            }));
-
-            args.push(taskCallback);
-
-            var task = tasks[taskIndex++];
-            task.apply(null, args);
-        }
-
-        nextTask([]);
-    }
-
-    var index = {
-        applyEach: applyEach,
-        applyEachSeries: applyEachSeries,
-        apply: apply$1,
-        asyncify: asyncify,
-        auto: auto,
-        autoInject: autoInject,
-        cargo: cargo,
-        compose: compose,
-        concat: concat,
-        concatSeries: concatSeries,
-        constant: constant,
-        detect: detect,
-        detectLimit: detectLimit,
-        detectSeries: detectSeries,
-        dir: dir,
-        doDuring: doDuring,
-        doUntil: doUntil,
-        doWhilst: doWhilst,
-        during: during,
-        each: each,
-        eachLimit: eachLimit,
-        eachOf: eachOf,
-        eachOfLimit: eachOfLimit,
-        eachOfSeries: eachOfSeries,
-        eachSeries: eachSeries,
-        ensureAsync: ensureAsync,
-        every: every,
-        everyLimit: everyLimit,
-        everySeries: everySeries,
-        filter: filter,
-        filterLimit: filterLimit,
-        filterSeries: filterSeries,
-        forever: forever,
-        iterator: iterator$1,
-        log: log,
-        map: map,
-        mapLimit: mapLimit,
-        mapSeries: mapSeries,
-        mapValues: mapValues,
-        mapValuesLimit: mapValuesLimit,
-        mapValuesSeries: mapValuesSeries,
-        memoize: memoize$1,
-        nextTick: nextTick,
-        parallel: parallel,
-        parallelLimit: parallelLimit,
-        priorityQueue: priorityQueue,
-        queue: queue$1,
-        race: race,
-        reduce: reduce,
-        reduceRight: reduceRight,
-        reflect: reflect,
-        reflectAll: reflectAll,
-        reject: reject,
-        rejectLimit: rejectLimit,
-        rejectSeries: rejectSeries,
-        retry: retry,
-        retryable: retryable,
-        seq: seq,
-        series: series,
-        setImmediate: setImmediate$1,
-        some: some,
-        someLimit: someLimit,
-        someSeries: someSeries,
-        sortBy: sortBy,
-        timeout: timeout,
-        times: times,
-        timesLimit: timeLimit,
-        timesSeries: timesSeries,
-        transform: transform,
-        unmemoize: unmemoize,
-        until: until,
-        waterfall: waterfall,
-        whilst: whilst,
-
-        // aliases
-        all: every,
-        any: some,
-        forEach: each,
-        forEachSeries: eachSeries,
-        forEachLimit: eachLimit,
-        forEachOf: eachOf,
-        forEachOfSeries: eachOfSeries,
-        forEachOfLimit: eachOfLimit,
-        inject: reduce,
-        foldl: reduce,
-        foldr: reduceRight,
-        select: filter,
-        selectLimit: filterLimit,
-        selectSeries: filterSeries,
-        wrapSync: asyncify
-    };
 
-    exports['default'] = index;
-    exports.applyEach = applyEach;
-    exports.applyEachSeries = applyEachSeries;
-    exports.apply = apply$1;
-    exports.asyncify = asyncify;
-    exports.auto = auto;
-    exports.autoInject = autoInject;
-    exports.cargo = cargo;
-    exports.compose = compose;
-    exports.concat = concat;
-    exports.concatSeries = concatSeries;
-    exports.constant = constant;
-    exports.detect = detect;
-    exports.detectLimit = detectLimit;
-    exports.detectSeries = detectSeries;
-    exports.dir = dir;
-    exports.doDuring = doDuring;
-    exports.doUntil = doUntil;
-    exports.doWhilst = doWhilst;
-    exports.during = during;
-    exports.each = each;
-    exports.eachLimit = eachLimit;
-    exports.eachOf = eachOf;
-    exports.eachOfLimit = eachOfLimit;
-    exports.eachOfSeries = eachOfSeries;
-    exports.eachSeries = eachSeries;
-    exports.ensureAsync = ensureAsync;
-    exports.every = every;
-    exports.everyLimit = everyLimit;
-    exports.everySeries = everySeries;
-    exports.filter = filter;
-    exports.filterLimit = filterLimit;
-    exports.filterSeries = filterSeries;
-    exports.forever = forever;
-    exports.iterator = iterator$1;
-    exports.log = log;
-    exports.map = map;
-    exports.mapLimit = mapLimit;
-    exports.mapSeries = mapSeries;
-    exports.mapValues = mapValues;
-    exports.mapValuesLimit = mapValuesLimit;
-    exports.mapValuesSeries = mapValuesSeries;
-    exports.memoize = memoize$1;
-    exports.nextTick = nextTick;
-    exports.parallel = parallel;
-    exports.parallelLimit = parallelLimit;
-    exports.priorityQueue = priorityQueue;
-    exports.queue = queue$1;
-    exports.race = race;
-    exports.reduce = reduce;
-    exports.reduceRight = reduceRight;
-    exports.reflect = reflect;
-    exports.reflectAll = reflectAll;
-    exports.reject = reject;
-    exports.rejectLimit = rejectLimit;
-    exports.rejectSeries = rejectSeries;
-    exports.retry = retry;
-    exports.retryable = retryable;
-    exports.seq = seq;
-    exports.series = series;
-    exports.setImmediate = setImmediate$1;
-    exports.some = some;
-    exports.someLimit = someLimit;
-    exports.someSeries = someSeries;
-    exports.sortBy = sortBy;
-    exports.timeout = timeout;
-    exports.times = times;
-    exports.timesLimit = timeLimit;
-    exports.timesSeries = timesSeries;
-    exports.transform = transform;
-    exports.unmemoize = unmemoize;
-    exports.until = until;
-    exports.waterfall = waterfall;
-    exports.whilst = whilst;
-    exports.all = every;
-    exports.allLimit = everyLimit;
-    exports.allSeries = everySeries;
-    exports.any = some;
-    exports.anyLimit = someLimit;
-    exports.anySeries = someSeries;
-    exports.find = detect;
-    exports.findLimit = detectLimit;
-    exports.findSeries = detectSeries;
-    exports.forEach = each;
-    exports.forEachSeries = eachSeries;
-    exports.forEachLimit = eachLimit;
-    exports.forEachOf = eachOf;
-    exports.forEachOfSeries = eachOfSeries;
-    exports.forEachOfLimit = eachOfLimit;
-    exports.inject = reduce;
-    exports.foldl = reduce;
-    exports.foldr = reduceRight;
-    exports.select = filter;
-    exports.selectLimit = filterLimit;
-    exports.selectSeries = filterSeries;
-    exports.wrapSync = asyncify;
+      nextTask([]);
+  }
+
+  var index = {
+    applyEach: applyEach,
+    applyEachSeries: applyEachSeries,
+    apply: apply$1,
+    asyncify: asyncify,
+    auto: auto,
+    autoInject: autoInject,
+    cargo: cargo,
+    compose: compose,
+    concat: concat,
+    concatSeries: concatSeries,
+    constant: constant,
+    detect: detect,
+    detectLimit: detectLimit,
+    detectSeries: detectSeries,
+    dir: dir,
+    doDuring: doDuring,
+    doUntil: doUntil,
+    doWhilst: doWhilst,
+    during: during,
+    each: each,
+    eachLimit: eachLimit,
+    eachOf: eachOf,
+    eachOfLimit: eachOfLimit,
+    eachOfSeries: eachOfSeries,
+    eachSeries: eachSeries,
+    ensureAsync: ensureAsync,
+    every: every,
+    everyLimit: everyLimit,
+    everySeries: everySeries,
+    filter: filter,
+    filterLimit: filterLimit,
+    filterSeries: filterSeries,
+    forever: forever,
+    iterator: iterator$1,
+    log: log,
+    map: map,
+    mapLimit: mapLimit,
+    mapSeries: mapSeries,
+    mapValues: mapValues,
+    mapValuesLimit: mapValuesLimit,
+    mapValuesSeries: mapValuesSeries,
+    memoize: memoize,
+    nextTick: nextTick,
+    parallel: parallel,
+    parallelLimit: parallelLimit,
+    priorityQueue: priorityQueue,
+    queue: queue$1,
+    race: race,
+    reduce: reduce,
+    reduceRight: reduceRight,
+    reflect: reflect,
+    reflectAll: reflectAll,
+    reject: reject,
+    rejectLimit: rejectLimit,
+    rejectSeries: rejectSeries,
+    retry: retry,
+    retryable: retryable,
+    seq: seq,
+    series: series,
+    setImmediate: setImmediate$1,
+    some: some,
+    someLimit: someLimit,
+    someSeries: someSeries,
+    sortBy: sortBy,
+    timeout: timeout,
+    times: times,
+    timesLimit: timeLimit,
+    timesSeries: timesSeries,
+    transform: transform,
+    unmemoize: unmemoize,
+    until: until,
+    waterfall: waterfall,
+    whilst: whilst,
+
+    // aliases
+    all: every,
+    any: some,
+    forEach: each,
+    forEachSeries: eachSeries,
+    forEachLimit: eachLimit,
+    forEachOf: eachOf,
+    forEachOfSeries: eachOfSeries,
+    forEachOfLimit: eachOfLimit,
+    inject: reduce,
+    foldl: reduce,
+    foldr: reduceRight,
+    select: filter,
+    selectLimit: filterLimit,
+    selectSeries: filterSeries,
+    wrapSync: asyncify
+  };
+
+  exports['default'] = index;
+  exports.applyEach = applyEach;
+  exports.applyEachSeries = applyEachSeries;
+  exports.apply = apply$1;
+  exports.asyncify = asyncify;
+  exports.auto = auto;
+  exports.autoInject = autoInject;
+  exports.cargo = cargo;
+  exports.compose = compose;
+  exports.concat = concat;
+  exports.concatSeries = concatSeries;
+  exports.constant = constant;
+  exports.detect = detect;
+  exports.detectLimit = detectLimit;
+  exports.detectSeries = detectSeries;
+  exports.dir = dir;
+  exports.doDuring = doDuring;
+  exports.doUntil = doUntil;
+  exports.doWhilst = doWhilst;
+  exports.during = during;
+  exports.each = each;
+  exports.eachLimit = eachLimit;
+  exports.eachOf = eachOf;
+  exports.eachOfLimit = eachOfLimit;
+  exports.eachOfSeries = eachOfSeries;
+  exports.eachSeries = eachSeries;
+  exports.ensureAsync = ensureAsync;
+  exports.every = every;
+  exports.everyLimit = everyLimit;
+  exports.everySeries = everySeries;
+  exports.filter = filter;
+  exports.filterLimit = filterLimit;
+  exports.filterSeries = filterSeries;
+  exports.forever = forever;
+  exports.iterator = iterator$1;
+  exports.log = log;
+  exports.map = map;
+  exports.mapLimit = mapLimit;
+  exports.mapSeries = mapSeries;
+  exports.mapValues = mapValues;
+  exports.mapValuesLimit = mapValuesLimit;
+  exports.mapValuesSeries = mapValuesSeries;
+  exports.memoize = memoize;
+  exports.nextTick = nextTick;
+  exports.parallel = parallel;
+  exports.parallelLimit = parallelLimit;
+  exports.priorityQueue = priorityQueue;
+  exports.queue = queue$1;
+  exports.race = race;
+  exports.reduce = reduce;
+  exports.reduceRight = reduceRight;
+  exports.reflect = reflect;
+  exports.reflectAll = reflectAll;
+  exports.reject = reject;
+  exports.rejectLimit = rejectLimit;
+  exports.rejectSeries = rejectSeries;
+  exports.retry = retry;
+  exports.retryable = retryable;
+  exports.seq = seq;
+  exports.series = series;
+  exports.setImmediate = setImmediate$1;
+  exports.some = some;
+  exports.someLimit = someLimit;
+  exports.someSeries = someSeries;
+  exports.sortBy = sortBy;
+  exports.timeout = timeout;
+  exports.times = times;
+  exports.timesLimit = timeLimit;
+  exports.timesSeries = timesSeries;
+  exports.transform = transform;
+  exports.unmemoize = unmemoize;
+  exports.until = until;
+  exports.waterfall = waterfall;
+  exports.whilst = whilst;
+  exports.all = every;
+  exports.allLimit = everyLimit;
+  exports.allSeries = everySeries;
+  exports.any = some;
+  exports.anyLimit = someLimit;
+  exports.anySeries = someSeries;
+  exports.find = detect;
+  exports.findLimit = detectLimit;
+  exports.findSeries = detectSeries;
+  exports.forEach = each;
+  exports.forEachSeries = eachSeries;
+  exports.forEachLimit = eachLimit;
+  exports.forEachOf = eachOf;
+  exports.forEachOfSeries = eachOfSeries;
+  exports.forEachOfLimit = eachOfLimit;
+  exports.inject = reduce;
+  exports.foldl = reduce;
+  exports.foldr = reduceRight;
+  exports.select = filter;
+  exports.selectLimit = filterLimit;
+  exports.selectSeries = filterSeries;
+  exports.wrapSync = asyncify;
 
 }));
\ No newline at end of file