code: public WordBuilder<I> append(Word<? extends I> word) {
          int wLen = word.length();
          ensureAdditionalCapacity(wLen);
          word.writeToArray(0, array, length, wLen);
          length += wLen;
          return this;
      }
docs: Appends a word to the contents of the internal storage.
  
  @param word
  the word to append.
  
  @return {@code this}