def call_from_executor(self, callback):
    self._calls_from_executor.append(callback)
    if self._schedule_pipe:
        os.write(self._schedule_pipe[1], b'x')
def call_from_executor(self, callback):
    self._calls_from_executor.append(callback)
    if self._schedule_pipe:
        os.write(self._schedule_pipe[1], b'x')