code: func (tx *Transaction) AddPort(port string, ofport uint, properties ...string) {
  	args := []string{"--if-exists", "del-port", port, "--", "add-port", tx.bridge, port, "--", "set", "Interface", port, fmt.Sprintf("ofport_request=%d", ofport)}
  	if len(properties) > 0 {
  		args = append(args, properties...)
  	}
  	tx.vsctlExec(args...)
  }
docs: // AddPort adds an interface to the bridge, requesting the indicated port
  // number, and optionally setting properties on it (as with "ovs-vsctl set
  // Interface ...").