code: public WordBuilder<I> repeatAppend(int num, Word<I> word) {
          if (num == 0) {
              return this;
          }
  
          int wLen = word.length();
          int allLen = wLen * num;
  
          ensureAdditionalCapacity(allLen);
  
          for (int i = num; i > 0; i--) {
              word.writeToArray(0, array, length, wLen);
              length += wLen;
          }
  
          return this;
      }
docs: Appends {@code num} copies of the given word to the contents of the initial storage.
  
  @param num
  the number of copies
  @param word
  the word
  
  @return {@code this}