@Nonnull
  @Override
  public Sketch<IntegerSummary> getResult() {
    return unionAll();
  }
@Test
  public void testThresholdBehavior() {
    IntegerSketch input1 = new IntegerSketch(_lgK, IntegerSummary.Mode.Sum);
    IntStream.range(0, 1000).forEach(i -> input1.update(i, 1));
    CompactSketch<IntegerSummary> sketch1 = input1.compact();
    IntegerSketch input2 = new IntegerSketch(_lgK, IntegerSummary.Mode.Sum);
    IntStream.range(1000, 2000).forEach(i -> input2.update(i, 1));
    CompactSketch<IntegerSummary> sketch2 = input2.compact();

    TupleIntSketchAccumulator accumulator = new TupleIntSketchAccumulator(_setOps, _nominalEntries, 3);
    accumulator.apply(sketch1);
    accumulator.apply(sketch2);

    Assert.assertEquals(accumulator.getResult().getEstimate(), sketch1.getEstimate() + sketch2.getEstimate());
  }