Method callback

tornado/process.py:296–303

(ret: int)

        future = Future()  # type: Future[int]

        def callback(ret: int) -> None:
            if ret != 0 and raise_error:
                # Unfortunately we don't have the original args any more.
                future_set_exception_unless_cancelled(
                    future, CalledProcessError(ret, "unknown")
                )
            else:
                future_set_result_unless_cancelled(future, ret)

        self.set_exit_callback(callback)
        return future