code: function SelectionField(type, options) {
    Field.call(this, type, options);
  
    this.arg = new Argument();
  
    this.menu = new Menu({
      document: this.document,
      maxPredictions: Conversion.maxPredictions
    });
    this.element = this.menu.element;
  
    this.onFieldChange = util.createEvent('SelectionField.onFieldChange');
  
    // i.e. Register this.onItemClick as the default action for a menu click
    this.menu.onItemClick.add(this.itemClicked, this);
  }
docs: A field that allows selection of one of a number of options