anchor.diff:                      new Token("(", TokenType.LBRACE),
                       new Token("100", TokenType.VAL),
                       new Token(")", TokenType.RBRACE)];
  -    
  +
       upnTokenStream2 = [new Token("x", TokenType.VAR),
                       new Token("*", TokenType.TIMES),
                       new Token("2", TokenType.VAL),
  
positive.code:   void initTests() {
      pars = new Parser();
      lex = new Lexer();
      inputString1 = "x + 2";
      inputString3 = "log(10)(100)";
      
      tokenStream1 = new List<Token>();
      tokenStream1.add(new Token("x", TokenType.VAR));
      tokenStream1.add(new Token("+", TokenType.PLUS));
      tokenStream1.add(new Token("2", TokenType.VAL));
      
      inputString2 = "x * 2^2.5 * log(10)(100)";
      tokenStream2 = [new Token("x", TokenType.VAR),
                      new Token("*", TokenType.TIMES),
                      new Token("2", TokenType.VAL),
  
negative.code:                     new Token("(", TokenType.LBRACE),
                      new Token("100", TokenType.VAL),
                      new Token(")", TokenType.RBRACE)];
  
      tokenStream3 = [new Token("log", TokenType.LOG),
                      new Token("(", TokenType.LBRACE),
                      new Token("10", TokenType.VAL),
                      new Token(")", TokenType.RBRACE),
                      new Token("(", TokenType.LBRACE),
                      new Token("100", TokenType.VAL),
                      new Token(")", TokenType.RBRACE)];
    }
  
    /*
     *  Tests and variables.
     */
    Parser pars;
    Lexer lex;
    String inputString1;
    String inputString2;
    String inputString3;
  
    List<Token> tokenStream1;
    List<Token> tokenStream2;
    List<Token> tokenStream3;
  
    List<Token> upnTokenStream1;
    List<Token> upnTokenStream2;
  
  
    void parserTokenTest() {
      List<Token> stream1 = lex.createTokenStream(inputString1);
      List<Token> stream2 = lex.createTokenStream(inputString2);
      List<Token> stream3 = lex.createTokenStream(inputString3);
  
      List<Token> upnStream1 = lex.shuntingYard(stream1);
      List<Token> upnStream2 = lex.shuntingYard(stream2);
  
      expect(stream1, orderedEquals(tokenStream1));
      expect(stream1, isNot(orderedEquals(tokenStream2)));
      expect(stream2, orderedEquals(tokenStream2));
      expect(stream2, isNot(orderedEquals(tokenStream1)));
      expect(stream3, orderedEquals(tokenStream3));
    }
  
    void parserExpressionTest() {
      throw new UnimplementedError();
    }
  
  
  }