code: def fit(self, users, items, user_features=None, item_features=None):
          
  
          self._user_id_mapping = {}
          self._item_id_mapping = {}
          self._user_feature_mapping = {}
          self._item_feature_mapping = {}
  
          return self.fit_partial(users, items, user_features, item_features)
docs: Fit the user/item id and feature name mappings.
  
          Calling fit the second time will reset existing mappings.
  
          Parameters
          ----------
  
          users: iterable of user ids
          items: iterable of item ids
          user_features: iterable of user features, optional
          item_features: iterable of item features, optional