@Nonnull
  @Override
  public CpcSketch getResult() {
    return unionAll();
  }
@Test
  public void testAccumulatorWithSingleSketch() {
    CpcSketch sketch = new CpcSketch(_lgNominalEntries);
    IntStream.range(0, 1000).forEach(sketch::update);

    CpcSketchAccumulator accumulator = new CpcSketchAccumulator(_lgNominalEntries, 2);
    accumulator.apply(sketch);

    Assert.assertFalse(accumulator.isEmpty());
    Assert.assertEquals(accumulator.getResult().getEstimate(), sketch.getEstimate());
  }