code: function(excludeWhole) {
  
        var whole, str = "";
        var n = this["n"];
        var d = this["d"];
        if (this["s"] < 0) {
          str += '-';
        }
  
        if (d === 1) {
          str += n;
        } else {
  
          if (excludeWhole && (whole = Math.floor(n / d)) > 0) {
            str += whole;
            str += " ";
            n %= d;
          }
  
          str += n;
          str += '/';
          str += d;
        }
        return str;
      }
docs: Returns a string-fraction representation of a Fraction object
  
  Ex: new Fraction("1.'3'").toFraction() => "4 1/3"