public Tree removeLargestKey() {
        String lKey = largestKey();
       if (size() == 1) {
            return new EmptyTree;
       } else {
            if (right.getKey().compareTo(lKey) == 0) {
                if (right.getLeft().isEmpty()) {
                    right = new EmptyTree();
                } else {
                    right = right.getLeft();
                }
            } else {
                right.removeLargestKey();
            }
       }