code: function highest(word) {
  
    word |= word >> 1;
    word |= word >> 2;
    word |= word >> 4;
    word |= word >> 8;
    word |= word >> 16;
  
    // We have to use a zero-fill right shift here, or the word will overflow when
    // the highest bit is in the leftmost position.
    return position((word >>> 1) + 1);
  
  }
docs: Returns the highest set bit in a word.