code: private static int lastSetWordIndex(int[] array) {
      int i = array.length - 1;
      for (; i >= 0 && wordAt(array, i) == 0; --i) { }
      return i;
    }
docs: Returns the index of the last word containing a true bit in an array, or -1 if none.
  
  @param array The array.
  @return The index of the last word containing a true bit, or -1 if none.