code: func (f *Form) GetButtonIndex(label string) int {
  	for index, button := range f.buttons {
  		if button.GetLabel() == label {
  			return index
  		}
  	}
  	return -1
  }
docs: // GetButtonIndex returns the index of the button with the given label, starting
  // with 0 for the button that was added first. If no such label was found, -1
  // is returned.