def UnmapDevicePort(device_port, device):
    """Unmaps a previously forwarded device port.

    Args:
      device: A DeviceUtils instance.
      device_port: A previously forwarded port (through Map()).
    """
    with _FileLock(Forwarder._LOCK_PATH):
      Forwarder._UnmapDevicePortLocked(device_port, device)