feat: await-able Async methods (#1572)

* make each and family awaitable

* dont pretend they're AsyncFunctions

* check errors

* ensure function name is preserved somehow

* awaitable concat

* awaitable detect

* awaitable every/filter

* awaitable groupBy

* awaitable map/mapValues

* awaitable reduce

* awaitable reject

* awaitable some

* awaitable transform

* awaitable times

* awaitable auto

* awaitable compose/seq

* awaitable whilst/until (lol)

* awaitable forever

* awaitable parallel/race

* awaitable retry

* awaitable series (lol)

* awaitable tryEach

* awaitable waterfall (lol)

* lint

* cleanup, remove noop and unused internal functions

1 files changed, 7 insertions, 4 deletions

diff --git a/lib/groupByLimit.js b/lib/groupByLimit.js
index f0402aa..24d5c40 100644
--- a/lib/groupByLimit.js
+++ b/lib/groupByLimit.js
@@ -1,6 +1,7 @@
-import noop from './internal/noop';
 import mapLimit from './mapLimit';
 import wrapAsync from './internal/wrapAsync';
+import awaitify from './internal/awaitify'
+
 /**
  * The same as [`groupBy`]{@link module:Collections.groupBy} but runs a maximum of `limit` async operations at a time.
  *
@@ -19,11 +20,11 @@ import wrapAsync from './internal/wrapAsync';
  * @param {Function} [callback] - A callback which is called when all `iteratee`
  * functions have finished, or an error occurs. Result is an `Object` whoses
  * properties are arrays of values which returned the corresponding key.
+ * @returns {Promise} a promise, if no callback is passed
  */
-export default function(coll, limit, iteratee, callback) {
-    callback = callback || noop;
+function groupByLimit(coll, limit, iteratee, callback) {
     var _iteratee = wrapAsync(iteratee);
-    mapLimit(coll, limit, (val, iterCb) => {
+    return mapLimit(coll, limit, (val, iterCb) => {
         _iteratee(val, (err, key) => {
             if (err) return iterCb(err);
             return iterCb(null, {key, val});
@@ -49,3 +50,5 @@ export default function(coll, limit, iteratee, callback) {
         return callback(err, result);
     });
 }
+
+export default awaitify(groupByLimit, 4);