Validates a state root, raising a ResponseFailed error if invalid.

        Args:
            state_root (str): The state_root to validate

        Raises:
            ResponseFailed: The state_root was invalid, and a status of
                INVALID_ROOT will be sent with the response.

def _validate_state_root(self, state_root):
        """Validates a state root, raising a ResponseFailed error if invalid.

        Args:
            state_root (str): The state_root to validate

        Raises:
            ResponseFailed: The state_root was invalid, and a status of
                INVALID_ROOT will be sent with the response.
        """
        if self._state_root_regex.fullmatch(state_root) is None:
            LOGGER.debug('Invalid state root: %s', state_root)
            raise _ResponseFailed(self._status.INVALID_ROOT)