code: func keycodesGet(xu *xgbutil.XUtil, keysym xproto.Keysym) []xproto.Keycode {
  	min, max := minMaxKeycodeGet(xu)
  	keyMap := KeyMapGet(xu)
  	if keyMap == nil {
  		panic("keybind.Initialize must be called before using the keybind " +
  			"package.")
  	}
  
  	var c byte
  	var keycode xproto.Keycode
  	keycodes := make([]xproto.Keycode, 0)
  	set := make(map[xproto.Keycode]bool, 0)
  
  	for kc := int(min); kc <= int(max); kc++ {
  		keycode = xproto.Keycode(kc)
  		for c = 0; c < keyMap.KeysymsPerKeycode; c++ {
  			if keysym == KeysymGet(xu, keycode, c) && !set[keycode] {
  				keycodes = append(keycodes, keycode)
  				set[keycode] = true
  			}
  		}
  	}
  	return keycodes
  }
docs: // Given a keysym, find all keycodes mapped to it in the current X environment.
  // keybind.Initialize MUST have been called before using this function.