How to use the pgctl.subprocess.Popen function in pgctl

def it_stays_locked_for_the_lifetime_of_subprocesses(self, tmpfile):
        from pgctl.subprocess import Popen

        with flock(tmpfile):
            p = Popen(('sleep', '99999'))
            assert p.poll() is None

            assert_locked(tmpfile)

        assert_locked(tmpfile)

        p.terminate()
        assert p.wait() == -15

        with flock(tmpfile):
            print('oh hi there!')

if not self.is_logger_running():
                Popen(
                    (
                        's6-supervise',
                        self.path.join('.log').strpath,
                    ),
                    env=self.supervise_env(lock, debug=False),
                    preexec_fn=functools.partial(
                        logger_preexec,
                        log_fifo_path,
                    ),
                    close_fds=True,
                )

            Popen(
                (
                    's6-supervise',
                    self.path.strpath,
                ),
                env=self.supervise_env(lock, debug=False),
                preexec_fn=functools.partial(
                    supervisor_preexec,
                    log_fifo_path,
                ),

def background(self):
        """Run supervise(1), while ensuring it is properly symlinked."""
        if self.supervised():
            return

        with self.flock() as lock:
            log_fifo_path = self.path.join('log_pipe').strpath

            try:
                os.mkfifo(log_fifo_path)
            except OSError as e:
                if e.errno != errno.EEXIST:
                    raise

            if not self.is_logger_running():
                Popen(
                    (
                        's6-supervise',
                        self.path.join('.log').strpath,
                    ),
                    env=self.supervise_env(lock, debug=False),
                    preexec_fn=functools.partial(
                        logger_preexec,
                        log_fifo_path,
                    ),
                    close_fds=True,
                )

            Popen(
                (
                    's6-supervise',
                    self.path.strpath,