@Test
public void testXor() {

  LongWritable curWritable = new LongWritable(0b000L);
  Assert.assertEquals(0b001L, xor.reduce(curWritable, new LongWritable(0b001L)).get());
  Assert.assertEquals(0b011L, xor.reduce(curWritable, new LongWritable(0b010L)).get());
  Assert.assertEquals(0b100L, xor.reduce(curWritable, new LongWritable(0b111L)).get());
}