code: def _join_tables(self, query: Query, join_models: Optional[List[type]]) -> Query:
          
          joined_query = query
          # Create the list of already joined entities
          joined_tables = [mapper.class_ for mapper in query._join_entities]
          if join_models:
              for j_model in join_models:
                  if not j_model in joined_tables:
                      # /!\ join return a new query /!\
                      joined_query = joined_query.join(j_model)
          return joined_query
docs: Method to make the join when relation is found.
  
          :param query: The sqlalchemy query.
          :type query: Query
  
          :param join_models: The list of joined models get from the method
              `_get_relation`.
          :type join_models: Optional[List[type]]
  
          :return: The new Query with the joined tables.
          :rtype: Query