public int[] unrank(final long rank) {
		final var T = new int[k];
		unrank(rank, T);
		return T;
	}
Return the k-subset for the given {@code rank}.

@param rank the k-subset rank
@return the k-subset for the given {@code rank}
@throws IllegalArgumentException if the given {@code rank} is invalid
        for {@code this} k-subset
jenetics.incubator/src/main/java/io/jenetics/incubator/combinatorial/KSubset.java