@_memoized_configured_property
    def _get_clause(self):
        params = [(primary_key, sql.bindparam(None, type_=primary_key.type))
                  for primary_key in self.primary_key]
        return sql.and_(*[k == v for (k, v) in params]), \
            util.column_dict(params)
create a "get clause" based on the primary key.  this is used
dataset/ETHPy150Open goFrendiAsgard/kokoropy/kokoropy/packages/sqlalchemy/orm/mapper.py/Mapper._get_clause