Python 加入类型注解后，父类到子类的强制转换怎么处理？

先贴代码：

class AbstractMapper(ABC): def __init__(self): self._loaded_map: Dict["ObjectId", "DomainObject"] = {} def _abstract_find(self, id_: "ObjectId") -> "DomainObject": stmt = self.find_statement() try: rs = cursor.execute(stmt, (id_,)).fetchone() res = self._load(rs) return res except Exception as e: ... finally: ... def _load(self, rs: tuple) -> "DomainObject": if rs[0] in self._loaded_map: return self._loaded_map[rs[0]] res = self._do_load(rs) self._loaded_map[res.id] = res return res @abstractmethod def _do_load(self, rs: tuple) -> "DomainObject": ... @abstractmethod def find_statement(self) -> str: ... class ArtistMapper(AbstractMapper): def find_statement(self) -> str: return "select id, name from artists where id = $1 limit 1" def _do_load(self, rs: tuple) -> "DomainObject": id_ = rs[0] name = rs[1] return Artist(id_, name) def find(self, id_) -> "Artist": return self._abstract_find(id_) # Expression of type "DomainObject" cannot be assigned to return type "Artist" "DomainObject" is incompatible with "Artist" 

上面的代码中，_abstract_find() 的返回值标注为 DomainObject 类型，而在 ArtistMapper 中 find 方法需要返回一个 Artist 实例，Artist 是 DomainObject 的子类。

我看到 Java 代码中这里是通过强制类型转换解决的，Python 中这样的代码虽然可以正确运行，但无法通过静态类型检查，想知道有什么办法可以通过检查？