message: use const in ES6 example
diff: "use strict"
  -var chevrotain = require("chevrotain")
  +const chevrotain = require("chevrotain")
  // ----------------- lexer -----------------
  -var Token = chevrotain.Token
  -var Lexer = chevrotain.Lexer
  -var Parser = chevrotain.Parser
  -
  +const Token = chevrotain.Token
  +const Lexer = chevrotain.Lexer
  +const Parser = chevrotain.Parser
  // With ES6 we can define Tokens using the class keywords.
  @@ -49,8 +48,8 @@ class WhiteSpace extends Token {}
  WhiteSpace.PATTERN = /\s+/
  WhiteSpace.GROUP = Lexer.SKIPPED // marking WhiteSpace as 'SKIPPED' makes the lexer skip it.
  -var allTokens = [WhiteSpace, NumberLiteral, StringLiteral, LCurly, RCurly, LSquare, RSquare, Comma, Colon, True, False, Null]
  -var JsonLexer = new Lexer(allTokens)
  +const allTokens = [WhiteSpace, NumberLiteral, StringLiteral, LCurly, RCurly, LSquare, RSquare, Comma, Colon, True, False, Null]
  +const JsonLexer = new Lexer(allTokens)
  // ----------------- parser -----------------
  // Using ES6 the parser too can be defined as a class
  @@ -60,7 +59,7 @@ class JsonParserES6 extends chevrotain.Parser {
  super(input, allTokens)
  // not mandatory, using $ (or any other sign) to reduce verbosity (this. this. this. this. .......)
  - var $ = this
  + const $ = this
  $.RULE("json", () => {
  $.OR([
  @@ -123,14 +122,14 @@ class JsonParserES6 extends chevrotain.Parser {
  // ----------------- wrapping it all together -----------------
  // reuse the same parser instance.
  -var parser = new JsonParserES6([])
  +const parser = new JsonParserES6([])
  module.exports = function(text) {
  - var lexResult = JsonLexer.tokenize(text)
  + const lexResult = JsonLexer.tokenize(text)
  // setting a new input will RESET the parser instance's state.
  parser.input = lexResult.tokens
  // any top level rule may be used as an entry point
  - var value = parser.json()
  + const value = parser.json()
  return {
  value: value, // this is a pure grammar, the value will always be <undefined>
  