if (counts[i] >= 0) {
          sortedCounts[index] += counts[i];
        } else {
          sortedCounts[index] = ~counts[i];
        }
      }
      // Note that we're not getting rid, yet, of elements with count 0.  We'll do that in build().
      this.elements = sortedElements;
      this.counts = sortedCounts;
      this.length = uniques;
    }

    /**