1 files changed, 13 insertions, 0 deletions
diff --git a/build-es/internal/concat.js b/build-es/internal/concat.js
new file mode 100644
index 0000000..482ad3a
--- /dev/null
+++ b/build-es/internal/concat.js
@@ -0,0 +1,13 @@
+'use strict';
+
+export default function concat(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);
+    });
+}