docs: static void clear(byte[][] blocks, int off, int len) {
      // this is significantly faster than looping or Arrays.fill (which loops), particularly when
      // the length of the slice to be cleared is <= to ARRAY_LEN (in that case, it's faster by a
      // factor of 2)
      int remaining = len;
      while (remaining > ARRAY_LEN) {
        System.arraycopy(NULL_ARRAY, 0, blocks, off, ARRAY_LEN);
        off += ARRAY_LEN;
        remaining -= ARRAY_LEN;
      }
  
      System.arraycopy(NULL_ARRAY, 0, blocks, off, remaining);
    }