"""领域异常。"""

from abc import ABCMeta


class AppException(Exception):
    """应用异常的基类。

    带上 HTTP 状态码。
    """

    status_code: int = 500

    def __init__(self, message: str) -> None:
        self.message = message


class NotFound(AppException):  # 行尾
    # 说明前面的注释
    """找不到资源。"""
    status_code = 404


@dataclass(frozen=True)
class Meta(Base, metaclass=ABCMeta):
    class Config:
        extra = "forbid"

    class _Hidden:
        pass


class _Private:
    pass


def factory():
    class Local:
        """局部类。"""
    return Local