code: function() {
      this.jsonInit({
        "message0": "%1",
        "args0": [
          {
            "type": "field_dropdown",
            "name": "BOOL",
            "options": [
              [Blockly.Msg.LOGIC_BOOLEAN_TRUE, "TRUE"],
              [Blockly.Msg.LOGIC_BOOLEAN_FALSE, "FALSE"]
            ]
          }
        ],
        "output": "Boolean",
        "colour": Blockly.Blocks.logic.HUE,
        "tooltip": Blockly.Msg.LOGIC_BOOLEAN_TOOLTIP,
        "helpUrl": Blockly.Msg.LOGIC_BOOLEAN_HELPURL
      });
    }
docs: Block for boolean data type: true and false.
  @this Blockly.Block