code: func Ungrab(xu *xgbutil.XUtil, win xproto.Window,
  	mods uint16, key xproto.Keycode) {
  
  	for _, m := range xevent.IgnoreMods {
  		xproto.UngrabKeyChecked(xu.Conn(), key, win, mods|m).Check()
  	}
  }
docs: // Ungrab undoes Grab. It will handle all combinations od modifiers found
  // in xevent.IgnoreMods.