'Used by workers to tell the service that the ActivityTask
identified by the taskToken has failed with reason (if
specified).
:type task_token: string
:param task_token: The taskToken of the ActivityTask.
:type details: string
:param details: Optional detailed information about the failure.
:type reason: string
:param reason: Description of the error that may assist in diagnostics.
:raises: UnknownResourceFault, SWFOperationNotPermittedError'

def respond_activity_task_failed(self, task_token, details=None, reason=None):

    return self.json_request('RespondActivityTaskFailed', {'taskToken': task_token, 'details': details, 'reason': reason})
