code: def existing_social_friends(self, user_social_auth=None, friend_ids=None):
          
          # Type check
          self.assert_user_is_social_auth_user(user_social_auth)
  
          if not friend_ids:
              friend_ids = self.fetch_social_friend_ids(user_social_auth)
  
          # Convert comma sepearated string to the list
          if isinstance(friend_ids, basestring):
              friend_ids = eval(friend_ids)
  
          # Match them with the ones on the website
          if USING_ALLAUTH:
              return User.objects.filter(socialaccount__uid__in=friend_ids).all()            
          else:
              return User.objects.filter(social_auth__uid__in=friend_ids).all()
docs: fetches and matches social friends
          if friend_ids is None, then fetches them from social network
  
          Return:
              User collection