'Handles an HTTP exception.  By default this will invoke the
registered error handlers and fall back to returning the
exception as response.
.. versionadded:: 0.3'

def handle_http_exception(self, e):

    if (e.code is None):
        return e
    handler = self._find_error_handler(e)
    if (handler is None):
        return e
    return handler(e)
