code: public DictionaryBuilder addWord(final String word, final int rank)
      {
          this.dictonary.put(word.toLowerCase(), rank);
          return this;
      }
docs: Add word to dictionary.
  
  @param word key to add to the dictionary, will be lowercased.
  @param rank the rank of the word in the dictionary.
  Should increment from most common to least common if ranked.
  If unranked, an example would be if there were 500 values in the dictionary, every word should have a rank of 250.
  If exclusion dictionary, rank is unimportant (set to 0).
  @return the builder