t.Parallel()
	b := dangerousSlice(t)
	for i := range b {
		idx := IndexByte(b[i:], 1)
		if idx != -1 {
			t.Fatalf("IndexByte(b[%d:])=%d, want -1\n", i, idx)
		}
	}
}

func TestIndexNearPageBoundary(t *testing.T) {
	t.Parallel()
	q := dangerousSlice(t)
	if len(q) > 64 {
		// Only worry about when we're near the end of a page.
		q = q[len(q)-64:]
	}
	b := dangerousSlice(t)
	if len(b) > 256 {