code: function() {
      this.jsonInit({
        "message0": "%1 %2",
        "args0": [
          {
            "type": "field_dropdown",
            "name": "OP",
            "options": [
              [Blockly.Msg.MATH_ROUND_OPERATOR_ROUND, 'ROUND'],
              [Blockly.Msg.MATH_ROUND_OPERATOR_ROUNDUP, 'ROUNDUP'],
              [Blockly.Msg.MATH_ROUND_OPERATOR_ROUNDDOWN, 'ROUNDDOWN']
            ]
          },
          {
            "type": "input_value",
            "name": "NUM",
            "check": "Number"
          }
        ],
        "output": "Number",
        "colour": Blockly.Blocks.math.HUE,
        "tooltip": Blockly.Msg.MATH_ROUND_TOOLTIP,
        "helpUrl": Blockly.Msg.MATH_ROUND_HELPURL
      });
    }
docs: Block for rounding functions.
  @this Blockly.Block