diff --git a/recommendation_engine.py b/recommendation_engine.py
index ece3b06..62dd371 100644
--- a/recommendation_engine.py
+++ b/recommendation_engine.py
@@ -255,7 +255,7 @@ class Engine:
         } for video in videos]
 
 
-    def update_user_playlists(user, watch_cutoff = 0.9):
+    def update_user_playlists(self, user, watch_cutoff = 0.9):
     # Output: playlists with updated in/out time of clips that have been watched.
     # Watched is defined as a video being played in full screen.
     # "watch_cutoff" parameter: the portion of the clip duration to be determined as watched the whole clip. should be [0,1]