@Override
    public BitMask reset(int index) {
        if (index < 64) {
            mask = mask & (Long.MAX_VALUE - (1L << index));
        }
        return this;
    }
@Test
  public void testReset() {
      assertThat(new LongBitMask().reset(0).toString()).isEqualTo("0");
      assertThat(new LongBitMask().reset(1).toString()).isEqualTo("0");
      assertThat(new LongBitMask().reset(65).toString()).isEqualTo("0");
  }