def poll(self):
        if self.returncode is not None:
            return self.returncode
        rcs = [proc.poll() for proc in self.procs]
        if any(rc not in None for rc in rcs):
            return None
        self.returncode = 0
        for rc in rcs:
            if rc != 0:
                self.returncode = rc
                break
        return self.returncode
dataset/ETHPy150Open tomerfiliba/plumbum/experiments/parallel.py/ConcurrentPopen.poll/operator `is` -> `not in`