code: function() {
      this.jsonInit({
        "type": "control_if_else",
        "message0": Blockly.Msg.CONTROL_IF,
        "message1": "%1",
        "message2": Blockly.Msg.CONTROL_ELSE,
        "message3": "%1",
        "args0": [
          {
            "type": "input_value",
            "name": "CONDITION",
            "check": "Boolean"
          }
        ],
        "args1": [
          {
            "type": "input_statement",
            "name": "SUBSTACK"
          }
        ],
        "args3": [
          {
            "type": "input_statement",
            "name": "SUBSTACK2"
          }
        ],
        "category": Blockly.Categories.control,
        "extensions": ["colours_control", "shape_statement"]
      });
    }
docs: Block for if-else.
  @this Blockly.Block