docs: protected static void binarySearch(ModifiableDoubleDBIDList index, DoubleDBIDListIter iter, double val) {
      // Binary search. TODO: move this into the DoubleDBIDList class.
      int left = 0, right = index.size();
      while(left < right) {
        final int mid = (left + right) >>> 1;
        final double curd = iter.seek(mid).doubleValue();
        if(val < curd) {
          right = mid;
        }
        else if(val > curd) {
          left = mid + 1;
        }
        else {
          left = mid;
          break;
        }
      }
      if(left >= index.size()) {
        --left;
      }
      iter.seek(left);
    }