def cancel_task(self, task_id):
self.registry.remove(task_id)<EOL>self._scheduler.cancel_job_task(task_id)<EOL>logger.info("<STR_LIT>", task_id)<EOL>
Cancel or 'un-schedule' a task.

        :param task_id: identifier of the task to cancel

        :raises NotFoundError: raised when the requested task is not
            found in the registry