code: function() {
      this.jsonInit({
        "message0": "%1",
        "args0": [
          {
            "type": "field_colour",
            "name": "COLOUR",
            "colour": "#ff0000"
          }
        ],
        "output": "Colour",
        "colour": Blockly.Blocks.colour.HUE,
        "helpUrl": Blockly.Msg.COLOUR_PICKER_HELPURL
      });
      // Assign 'this' to a variable for use in the tooltip closure below.
      var thisBlock = this;
      // Colour block is trivial.  Use tooltip of parent block if it exists.
      this.setTooltip(function() {
        var parent = thisBlock.getParent();
        return (parent && parent.tooltip) || Blockly.Msg.COLOUR_PICKER_TOOLTIP;
      });
    }
docs: Block for colour picker.
  @this Blockly.Block