p := make([]int, 30)
		for i := range p {
			p[i] = i
		}
		r.Shuffle(30, func(i, j int) { p[i], p[j] = p[j], p[i] })
	}
}

// BenchmarkShuffleOverhead uses a minimal swap function
// to measure just the shuffling overhead.
func BenchmarkShuffleOverhead(b *testing.B) {
	r := New(NewSource(1))
	for n := b.N; n > 0; n-- {
		r.Shuffle(52, func(i, j int) {
			if i < 0 || i >= 52 || j < 0 || j >= 52 {

		for i := range p {
			p[i] = i
		}
		r.Shuffle(30, func(i, j int) { p[i], p[j] = p[j], p[i] })
		t += p[0]
	}
	Sink = uint64(t)
}

// BenchmarkShuffleOverhead uses a minimal swap function
// to measure just the shuffling overhead.
func BenchmarkShuffleOverhead(b *testing.B) {
	r := testRand()
	for n := b.N; n > 0; n-- {
		r.Shuffle(30, func(i, j int) {
			if i < 0 || i >= 30 || j < 0 || j >= 30 {