Word left = new Word("Dog");
Set<Word> right = new HashSet<>();
right.add(new Word("Hound"));
right.add(new Word("Mutt"));
right.add(new Word("Pooch"));

// Write some code to call add(Word, Word) for each Word in the Set, such that
// in this case you end up with:
//   add(Dog, Hound);
//   add(Dog, Mutt);
//   add(Dog, Pooch);