code: def _validate_state_root(self, state_root):
          
          if self._state_root_regex.fullmatch(state_root) is None:
              LOGGER.debug('Invalid state root: %s', state_root)
              raise _ResponseFailed(self._status.INVALID_ROOT)
docs: 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.