code: private int findKey(K key) {
      int i = 0;
      for (K otherKey : this.keys) {
        if (this.comparator.compare(key, otherKey) == 0) {
          return i;
        }
        i++;
      }
      return -1;
    }
docs: This does a linear scan which is simpler than a binary search. For a small collection size this
  still should be as fast as binary search.