docs: def live_pidfile(pidfile): # pragma: no cover
      """(pidfile:str) -> int | None
      Returns an int found in the named file, if there is one,
      and if there is a running process with that process id.
      Return None if no such process exists.
      """
      pid = read_pidfile(pidfile)
      if pid:
          try:
              kill(int(pid), 0)
              return pid
          except OSError as e:
              if e.errno == errno.EPERM:
                  return pid
      return None