### Question:
UInt64 implements Comparable<UInt64> { public UInt64 decrement() { return minus(1); } private  UInt64(final long value); static UInt64 valueOf(final long value); static UInt64 valueOf(final String value); static UInt64 valueOf(final BigInteger value); static UInt64 fromLongBits(final long value); UInt64 plus(final long other); UInt64 increment(); UInt64 decrement(); UInt64 plus(final UInt64 other); UInt64 minus(final long other); UInt64 minus(final UInt64 other); UInt64 times(final long other); UInt64 times(final UInt64 other); UInt64 dividedBy(final long divisor); UInt64 dividedBy(final UInt64 divisor); UInt64 mod(final long divisor); UInt64 mod(final UInt64 divisor); UInt64 max(final UInt64 other); UInt64 max(final long other); UInt64 min(final UInt64 other); UInt64 min(final long other); @Override int compareTo(final UInt64 o); boolean isGreaterThan(final UInt64 other); boolean isGreaterThanOrEqualTo(final UInt64 other); boolean isLessThan(final UInt64 other); boolean isLessThanOrEqualTo(final UInt64 other); long longValue(); int intValue(); BigInteger bigIntegerValue(); @Override boolean equals(final Object o); @Override int hashCode(); @Override String toString(); static final int BYTES; static final UInt64 ZERO; static final UInt64 ONE; static final UInt64 MAX_VALUE; }### Answer:
@Test void decrement() { assertThat(UInt64.ONE.decrement()).isEqualTo(UInt64.ZERO); assertThat(UInt64.valueOf(3).decrement().decrement()).isEqualTo(UInt64.ONE); }