def _get_exc_class_and_code(
        exc_class_or_code: type[Exception] | int,
    ) -> tuple[type[Exception], int | None]:
        """Get the exception class being handled. For HTTP status codes
        or ``HTTPException`` subclasses, return both the exception and
        status code.

        :param exc_class_or_code: Any exception class, or an HTTP status
            code as an integer.
        """
        exc_class: type[Exception]

        if isinstance(exc_class_or_code, int):
            try:
                exc_class = default_exceptions[exc_class_or_code]
            except KeyError:
                raise ValueError(
                    f"'{exc_class_or_code}' is not a recognized HTTP"
                    " error code. Use a subclass of HTTPException with"
                    " that code instead."
                ) from None
        else:
            exc_class = exc_class_or_code

        if isinstance(exc_class, Exception):
            raise TypeError(
                f"{exc_class!r} is an instance, not a class. Handlers"
                " can only be registered for Exception classes or HTTP"
                " error codes."
            )

        if not issubclass(exc_class, Exception):
            raise ValueError(
                f"'{exc_class.__name__}' is not a subclass of Exception."
                " Handlers can only be registered for Exception classes"
                " or HTTP error codes."
            )

        if issubclass(exc_class, HTTPException):
            return exc_class, exc_class.code
        else:
            return exc_class, None
Get the exception class being handled. For HTTP status codes
        or ``HTTPException`` subclasses, return both the exception and
        status code.

        :param exc_class_or_code: Any exception class, or an HTTP status
            code as an integer.
        
src/flask/sansio/scaffold.py