I'm trying to eliminate the by default value for options to see if that's where the problem arises.

playlists_mismatch.py

@@ -7,7 +7,7 @@ from googleapiclient.errors import HttpError
 import datetime
 api_key = os.getenv("api_key_secret")
 youtube = build('youtube', 'v3', developerKey=api_key)
-def playlists_mismatch_func(playlistlink1, playlistlink2, output = 'link'):
+def playlists_mismatch_func(playlistlink1, playlistlink2, output):
     """Return the ids of videos that are only one of the playlists, and not in the other"""
     
     def extract_playlist_id(playlistlink):