async is a keyword on 3.7 (#47)

hroncok · fxdgear · commit 7c5adacadcd1 · 2018-08-08T11:16:53.000-06:00
Fixes #44
diff --git a/elasticsearch_async/helpers.py b/elasticsearch_async/helpers.py
@@ -1,3 +1,4 @@
 import asyncio
 
-ensure_future = getattr(asyncio, 'ensure_future', asyncio.async)
+ensure_future = (getattr(asyncio, 'ensure_future', None) or
+                 getattr(asyncio, 'async', None))
