fmt.Printf("Cut(%q, %q) = %q, %q, %v\n", s, sep, before, after, found)
	}
	show("Gopher", "Go")
	show("Gopher", "ph")
	show("Gopher", "er")
	show("Gopher", "Badger")
	// Output:
	// Cut("Gopher", "Go") = "", "pher", true
	// Cut("Gopher", "ph") = "Go", "er", true
	// Cut("Gopher", "er") = "Goph", "", true
	// Cut("Gopher", "Badger") = "Gopher", "", false
}

func ExampleCutPrefix() {
	show := func(s, sep string) {

	os.Setenv("GO_ADDR2LINETEST_IS_ADDR2LINE", "1") // Set for subprocesses to inherit.
	os.Exit(m.Run())
}

// addr2linePath returns the path to the "addr2line" binary to run.
func addr2linePath(t testing.TB) string {
	t.Helper()
	testenv.MustHaveExec(t)

	addr2linePathOnce.Do(func() {
		addr2lineExePath, addr2linePathErr = os.Executable()
	})
	if addr2linePathErr != nil {
		t.Fatal(addr2linePathErr)
	}
	return addr2lineExePath
}

		fmt.Fprintln(os.Stderr, "reading standard input:", err)
	}
}

// Return the most recent call to Scan as a []byte.
func ExampleScanner_Bytes() {
	scanner := bufio.NewScanner(strings.NewReader("gopher"))
	for scanner.Scan() {
		fmt.Println(len(scanner.Bytes()) == 6)
	}
	if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "shouldn't see an error scanning a string")
	}
	// Output:
	// true
}

		if f.ModifiedTime != 0 || f.ModifiedDate != 0 {
			f.Modified = modified.In(timeZone(msdosModified.Sub(modified)))
		}
	}

	// Assume that uncompressed size 2³²-1 could plausibly happen in
	// an old zip32 file that was sharding inputs into the largest chunks
	// possible (or is just malicious; search the web for 42.zip).
	// If needUSize is true still, it means we didn't see a zip64 extension.

}

func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }

func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) }

func BenchmarkToUpper(b *testing.B) {
	for _, tc := range upperTests {
		tin := []byte(tc.in)
		b.Run(tc.in, func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				actual := ToUpper(tin)
				if !Equal(actual, tc.out) {

	// Create and add some files to the archive.
	var buf bytes.Buffer
	tw := tar.NewWriter(&buf)
	var files = []struct {
		Name, Body string
	}{
		{"readme.txt", "This archive contains some text files."},
		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
		{"todo.txt", "Get animal handling license."},
	}
	for _, file := range files {
		hdr := &tar.Header{
			Name: file.Name,
			Mode: 0600,
			Size: int64(len(file.Body)),

			// should not happen
			t.Fatal(err)
		}
		tt.f(reader)
		err := reader.UnreadRune()
		if err == nil {
			t.Errorf("Unreading after %s: expected error", tt.name)
		}
	}
}

func TestReaderDoubleUnreadRune(t *testing.T) {
	buf := NewBuffer([]byte("groucho"))
	if _, _, err := buf.ReadRune(); err != nil {
		// should not happen
		t.Fatal(err)
	}

}

// operand parses a general operand and stores the result in *a.
func (p *Parser) operand(a *obj.Addr) {
	//fmt.Printf("Operand: %v\n", p.input)
	if len(p.input) == 0 {
		p.errorf("empty operand: cannot happen")
		return
	}
	// General address (with a few exceptions) looks like
	//	$sym±offset(SB)(reg)(index*scale)
	// Exceptions are:
	//
	//	R1
	//	offset
	//	$offset

	tok := in.Stack.Next()
	if tok != scanner.Int {
		in.expectText("expected line number after #line")
	}
	line, err := strconv.Atoi(in.Stack.Text())
	if err != nil {
		in.Error("error parsing #line (cannot happen):", err)
	}
	tok = in.Stack.Next()
	if tok != scanner.String {
		in.expectText("expected file name in #line")
	}
	file, err := strconv.Unquote(in.Stack.Text())
	if err != nil {

	var f formatter
	blk := tw.templateV7Plus(hdr, f.formatString, f.formatOctal)
	f.formatString(blk.toUSTAR().prefix(), namePrefix)
	blk.setFormat(FormatUSTAR)
	if f.err != nil {
		return f.err // Should never happen since header is validated
	}
	return tw.writeRawHeader(blk, hdr.Size, hdr.Typeflag)
}

func (tw *Writer) writePAXHeader(hdr *Header, paxHdrs map[string]string) error {
	realName, realSize := hdr.Name, hdr.Size