code: function(a, b) {
  
        parse(a, b);
        return new Fraction(
                this["s"] * this["n"] * P["d"] + P["s"] * this["d"] * P["n"],
                this["d"] * P["d"]
                );
      }
docs: Adds two rational numbers
  
  Ex: new Fraction({n: 2, d: 3}).add("14.9") => 467 / 30