code: function() {
      this.setColour(Blockly.Blocks.lists.HUE);
      this.appendDummyInput()
          .appendField(Blockly.Msg.LISTS_CREATE_WITH_ITEM_TITLE);
      this.setPreviousStatement(true);
      this.setNextStatement(true);
      this.setTooltip(Blockly.Msg.LISTS_CREATE_WITH_ITEM_TOOLTIP);
      this.contextMenu = false;
    }
docs: Mutator bolck for adding items.
  @this Blockly.Block