code: func LabelNewWithMnemonic(str string) (*Label, error) {
  	cstr := C.CString(str)
  	defer C.free(unsafe.Pointer(cstr))
  	c := C.gtk_label_new_with_mnemonic((*C.gchar)(cstr))
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	obj := glib.Take(unsafe.Pointer(c))
  	return wrapLabel(obj), nil
  }
docs: // LabelNewWithMnemonic is a wrapper around gtk_label_new_with_mnemonic().