add method

Implementation

Fraction add(Fraction otherParsed) {
  if (denominator == otherParsed.denominator) {
    return Fraction(numerator + otherParsed.numerator,
        denominator: denominator);
  }
  return Fraction(
      (numerator * otherParsed.denominator) +
          (otherParsed.numerator * denominator),
      denominator: denominator * otherParsed.denominator);
}