anchor.diff:   * A Token consists of text and has a [TokenType].
    */
   class Token {
  -  /// The test of this token.
  +  /// The text of this token.
     String text;
     
     /// The type of this token.
  
positive.code: 
      for (var i = 0; i < inputStream.length; i++){
        Token currentToken = inputStream[i];
  
        if(currentToken.type == TokenType.VAL) {
          Expression currentExpression = new Number(double.parse(currentToken.text));
          expressionStack.add(currentExpression);
          continue;
        }
  
negative.code:     keywords["*"] = TokenType.TIMES;
      keywords["/"] = TokenType.DIV;
      keywords["^"] = TokenType.POW;
      keywords["rt"] = TokenType.ROOT;
      keywords["sqrt"] = TokenType.SQRT;
      keywords["log"] = TokenType.LOG;
      keywords["cos"] = TokenType.COS;
      keywords["sin"] = TokenType.SIN;
      keywords["tan"] = TokenType.TAN;
      keywords["ln"] = TokenType.LN;
      keywords["exp"] = TokenType.EFUNC;
      keywords["("] = TokenType.LBRACE;
      keywords[")"] = TokenType.RBRACE;
      keywords["{"] = TokenType.LBRACE;
  