code: func (i *InputField) SetDoneFunc(handler func(key tcell.Key)) *InputField {
  	i.done = handler
  	return i
  }
docs: // SetDoneFunc sets a handler which is called when the user is done entering
  // text. The callback function is provided with the key that was pressed, which
  // is one of the following:
  //
  //   - KeyEnter: Done entering text.
  //   - KeyEscape: Abort text input.
  //   - KeyTab: Move to the next field.
  //   - KeyBacktab: Move to the previous field.