> I didn't understand this sentences: "setting a value in ProcessOpen.terminate() implies that the process no longer runs. However it will actually no longer be running when os.waitpid() will be called and collect the child process (until then it's a zombie)."

If I understood well, we consider a process to be running when `ProcessOpen.returncode is None`. It made me add the `ProcessOpen.is_running` property to make it clearer.

Do I misunderstood  the meaning of `.returncode`?