def poll(self, _deadstate=None):
        if self.sts < 0:
            result = self._popen.poll(_deadstate)
            if result is not None:
                self.sts = result
        return self.sts
Return the exit status of the child process if it has finished,
dataset/ETHPy150Open azoft-dev-team/imagrium/env/Lib/popen2.py/Popen3.poll