(pid, fd) = pty.fork() # os.forkpty()
print('os.get_inheritable(fd))

def fork():
    """fork() -> (pid, master_fd)
    Fork and make the child a session leader with a controlling terminal."""
    try:
        pid, fd = os.forkpty()
    except (AttributeError, OSError):
        pass
    else:
        if pid == CHILD:
            try:
                os.setsid()
            except OSError:
                # os.forkpty() already set us session leader
                pass
        return pid, fd
    master_fd, slave_fd = openpty()
    pid = os.fork()
    if pid == CHILD:
        os.close(master_fd)
        os.login_tty(slave_fd)
    else:
        os.close(slave_fd)
    # Parent and child process.
    return pid, master_fd