if err := WriteFile(filepath.Join(d, "control.txt"), []byte(string("Hello, world!")), 0644); err != nil {
		t.Fatal(err)
	}
	if err := WriteFile(filepath.Join(d, `e:xperi\ment.txt`), []byte(string("Hello, colon and backslash!")), 0644); err != nil {
		t.Fatal(err)
	}

	fsys := DirFS(d)
	err := fs.WalkDir(fsys, ".", func(path string, e fs.DirEntry, err error) error {
		if fs.ValidPath(e.Name()) {

		{"foo\x00bar: foo\r\n", 400},                         // binary in header
		{"Foo: " + strings.Repeat("x", 1<<21) + "\r\n", 431}, // header too large
		// Spaces between the header key and colon are not allowed.
		// See RFC 7230, Section 3.2.4.
		{"Foo : bar\r\n", 400},
		{"Foo\t: bar\r\n", 400},

		// Empty header keys are invalid.
		// See RFC 7230, Section 3.2.
		{": empty key\r\n", 400},

	if rule1.Comment == nil || rule2.Comment == nil {
		return false
	}
	name1, name2 := rule1.Comment.Value, rule2.Comment.Value

	// The service name is the comment up to the first space or colon
	i := strings.IndexAny(name1, " :")
	if i != -1 {
		name1 = name1[:i]
	}
	i = strings.IndexAny(name2, " :")
	if i != -1 {
		name2 = name2[:i]
	}

	return name1 < name2
}

	// valid, however.
	Truncated bool
}

// PseudoValue returns the given pseudo header field's value.
// The provided pseudo field should not contain the leading colon.
func (mh *http2MetaHeadersFrame) PseudoValue(pseudo string) string {
	for _, hf := range mh.Fields {
		if !hf.IsPseudo() {
			return ""
		}
		if hf.Name[1:] == pseudo {
			return hf.Value
		}