code: function() {
      this.setHelpUrl(Blockly.Msg.COLOUR_RGB_HELPURL);
      this.setColour(Blockly.Blocks.colour.HUE);
      this.appendValueInput('RED')
          .setCheck('Number')
          .setAlign(Blockly.ALIGN_RIGHT)
          .appendField(Blockly.Msg.COLOUR_RGB_TITLE)
          .appendField(Blockly.Msg.COLOUR_RGB_RED);
      this.appendValueInput('GREEN')
          .setCheck('Number')
          .setAlign(Blockly.ALIGN_RIGHT)
          .appendField(Blockly.Msg.COLOUR_RGB_GREEN);
      this.appendValueInput('BLUE')
          .setCheck('Number')
          .setAlign(Blockly.ALIGN_RIGHT)
          .appendField(Blockly.Msg.COLOUR_RGB_BLUE);
      this.setOutput(true, 'Colour');
      this.setTooltip(Blockly.Msg.COLOUR_RGB_TOOLTIP);
    }
docs: Block for composing a colour from RGB components.
  @this Blockly.Block