@classmethod
def update_many(cls, match_query_dict, update_expression_dict):
    """
        updates multiple documents in the database
        :param match_query_dict: the query expression to match the documents to be updated
        :param update_expression_dict:
        :return: the number of modified documents
        """
    update_result = cls.get_collection().update_many(match_query_dict,
        update_expression_dict)
    return update_result.modified_count
