def METHOD_NAME():
    """Verifies that we are the single running navtopology process.
    If a navtopology process is already running, we exit this process.
    """
    try:
        daemon.justme(PID_FILE)
    except daemon.AlreadyRunningError as error:
        print("navtopology is already running (%d)" % error.pid, file=sys.stderr)
        sys.exit(1)
    daemon.writepidfile(PID_FILE)
    atexit.register(daemon.daemonexit, PID_FILE)