code: func (l *List) SetSelectedFunc(handler func(int, string, string, rune)) *List {
  	l.selected = handler
  	return l
  }
docs: // SetSelectedFunc sets the function which is called when the user selects a
  // list item by pressing Enter on the current selection. The function receives
  // the item's index in the list of items (starting with 0), its main text,
  // secondary text, and its shortcut rune.