fixed a missing import.

shizhiw · shizhiw · commit a45cafb38a1a · 2018-10-09T16:58:10.000-07:00
diff --git a/official/recommendation/data_async_generation.py b/official/recommendation/data_async_generation.py
@@ -43,6 +43,7 @@
 from official.datasets import movielens
 from official.recommendation import constants as rconst
 from official.recommendation import stat_utils
+from official.recommendation import popen_helper
 
 
 _log_file = None
