def errorhandler(self, code_or_exception):
        """
        Registers an error handler that becomes active for this bundle
        only.  Please be aware that routing does not happen local to a
        bundle so an error handler for 404 usually is not handled by
        a bundle unless it is caused inside a view function.  Another
        special case is the 500 internal server error which is always looked
        up from the application.

        Otherwise works as the :meth:`flask.Blueprint.errorhandler` decorator.
        """
        def decorator(fn):
            self._defer(lambda bp: bp.register_error_handler(code_or_exception, fn))
            return fn
        return decorator
Registers an error handler that becomes active for this bundle
        only.  Please be aware that routing does not happen local to a
        bundle so an error handler for 404 usually is not handled by
        a bundle unless it is caused inside a view function.  Another
        special case is the 500 internal server error which is always looked
        up from the application.

        Otherwise works as the :meth:`flask.Blueprint.errorhandler` decorator.