t.Fatal(err)
	}
	defer RemoveAll(tempDir)
	filename := filepath.Join(tempDir, "blurp.txt")

	shmorp := []byte("shmorp")
	florp := []byte("florp")
	err = WriteFile(filename, shmorp, 0444)
	if err != nil {
		t.Fatalf("WriteFile %s: %v", filename, err)
	}
	err = WriteFile(filename, florp, 0444)
	if err == nil {
		t.Fatalf("Expected an error when writing to read-only file %s", filename)
	}
	got, err := ReadFile(filename)

	return !found
}

func scan(min, max rune) (rang, except []uint32) {
	lo := rune(-1)
	for i := min; ; i++ {
		if (i > max || !unicode.IsPrint(i)) && lo >= 0 {
			// End range, but avoid flip flop.
			if i+1 <= max && unicode.IsPrint(i+1) {
				except = append(except, uint32(i))
				continue
			}
			rang = append(rang, uint32(lo), uint32(i-1))
			lo = -1
		}
		if i > max {
			break
		}