code: function() {
      this.jsonInit({
        "message0": "%1",
        "args0": [
          {
            "type": "field_variable",
            "name": "CLONE_NAME_OPTION",
            "variableTypes": [Blockly.CLONE_NAME_VARIABLE_TYPE],
            "variable": Blockly.Msg.DEFAULT_CLONE_NAME
          }
        ],
        "colour": Blockly.Colours.control.secondary,
        "colourSecondary": Blockly.Colours.control.secondary,
        "colourTertiary": Blockly.Colours.control.tertiary,
        "extensions": ["output_string"]
      });
    }
docs: Clone name selection menu.
  @this Blockly.Block