code: function() {
      var OPERATORS = this.RTL ? [
            ['=', 'EQ'],
            ['\u2260', 'NEQ'],
            ['>', 'LT'],
            ['\u2265', 'LTE'],
            ['<', 'GT'],
            ['\u2264', 'GTE']
          ] : [
            ['=', 'EQ'],
            ['\u2260', 'NEQ'],
            ['<', 'LT'],
            ['\u2264', 'LTE'],
            ['>', 'GT'],
            ['\u2265', 'GTE']
          ];
      this.setHelpUrl(Blockly.Msg.LOGIC_COMPARE_HELPURL);
      this.setColour(Blockly.Blocks.logic.HUE);
      this.setOutput(true, 'Boolean');
      this.appendValueInput('A');
      this.appendValueInput('B')
          .appendField(new Blockly.FieldDropdown(OPERATORS), 'OP');
      this.setInputsInline(true);
      // Assign 'this' to a variable for use in the tooltip closure below.
      var thisBlock = this;
      this.setTooltip(function() {
        var op = thisBlock.getFieldValue('OP');
        var TOOLTIPS = {
          'EQ': Blockly.Msg.LOGIC_COMPARE_TOOLTIP_EQ,
          'NEQ': Blockly.Msg.LOGIC_COMPARE_TOOLTIP_NEQ,
          'LT': Blockly.Msg.LOGIC_COMPARE_TOOLTIP_LT,
          'LTE': Blockly.Msg.LOGIC_COMPARE_TOOLTIP_LTE,
          'GT': Blockly.Msg.LOGIC_COMPARE_TOOLTIP_GT,
          'GTE': Blockly.Msg.LOGIC_COMPARE_TOOLTIP_GTE
        };
        return TOOLTIPS[op];
      });
      this.prevBlocks_ = [null, null];
    }
docs: Block for comparison operator.
  @this Blockly.Block