Define four static methods, named add, subtract, multiply, and divide. Each of these methods should be defined to take two Fraction arguments and return a new Fraction. For now, though, each of these methods should return null. Define a constructor that takes two int parameters, corresponding to the numerator and denominator of a fraction. For now, the constructor should do nothing with these parameters; the constructor body should be empty. You may think this odd, but the reasons will be explained shortly. Define one more static method to compute the greatest common divisor and name it gcd. The method should take two int parameters and return an int result. A Java implementation of gcd that uses Euclids Algorithm is provided when you get to the testing portion of this assignment. Finally, define an equals method, with exactly this signature: @Override public boolean equals(Object o) { ... }