docs: function quantizedIndex(i) {
      if(i < 1) { return 0; }
      var group = Math.floor(Math.log(i) / Math.LN10),
          offset = i/(2.5 * Math.pow(10, group));
      if(offset >= 3) {
        group++;
        offset = 0;
      }
      return 3*group + Math.round(Math.min(2, offset));
    }