@Override
    public void merge(NormalSketch other) {
        Preconditions.checkArgument(data.length == other.data.length,
                "Trying to merge sketch with one of different size. Expected %s, actual %s", data.length, other.data.length);
        for (int i = 0; i < data.length; i++) {
            data[i] = (byte) Math.max(data[i], other.data[i]);
        }
    }
@Test(expected = IllegalArgumentException.class)
    public void requireThatMergingFailsForSketchesOfDifferentSize() {
        NormalSketch s1 = new NormalSketch(2);
        NormalSketch s2 = new NormalSketch(3);
        s1.merge(s2);
    }