behavior has changed based on a non-default value
for that setting.
For example, when `GODEBUG=http2client=0` is set,
`/godebug/non-default-behavior/http2client:events`
counts the number of HTTP transports that the program
has configured without HTTP/2 support.

## Default GODEBUG Values {#default}

When a GODEBUG setting is not listed in the environment variable,
its value is derived from three sources:

func (s *Scanner) Text() string {
	return string(s.token)
}

// ErrFinalToken is a special sentinel error value. It is intended to be
// returned by a Split function to indicate that the scanning should stop
// with no error. If the token being delivered with this error is not nil,
// the token is the last token.
//
// The value is useful to stop processing early or when it is necessary to

	if err := tw.writeRawHeader(&tw.blk, int64(len(data)), flag); err != nil {
		return err
	}
	_, err := io.WriteString(tw, data)
	return err
}

// writeRawHeader writes the value of blk, regardless of its value.
// It sets up the Writer such that it can accept a file of the given size.
// If the flag is a special header-only flag, then the size is treated as zero.

// allowedFormats determines which formats can be used.
// The value returned is the logical OR of multiple possible formats.
// If the value is FormatUnknown, then the input Header cannot be encoded
// and an error is returned explaining why.
//
// As a by-product of checking the fields, this function returns paxHdrs, which
// contain all fields that could not be directly encoded.

func testEmptyTokens(t *testing.T, text string, values []string) {
	s := NewScanner(strings.NewReader(text))
	s.Split(commaSplit)
	var i int
	for i = 0; s.Scan(); i++ {
		if i >= len(values) {
			t.Fatalf("got %d fields, expected %d", i+1, len(values))
		}
		if s.Text() != values[i] {
			t.Errorf("%d: expected %q got %q", i, values[i], s.Text())
		}
	}
	if i != len(values) {

in an unspecified order.
This means that races on multiword data structures
can lead to inconsistent values not corresponding to a single write.
When the values depend on the consistency
of internal (pointer, length) or (pointer, type) pairs,
as can be the case for interface values, maps,
slices, and strings in most Go implementations,
such races can in turn lead to arbitrary memory corruption.
</p>

<p>

		return "", fmt.Errorf("failed to parse ideviceinstaller output: %v", err)
	}
	for _, app := range list.Apps {
		values, err := parsePlistDict(app.Data)
		if err != nil {
			return "", fmt.Errorf("findDeviceAppPath: failed to parse app dict: %v", err)
		}
		if values["CFBundleIdentifier"] == bundleID {
			if path, ok := values["Path"]; ok {
				return path, nil
			}
		}
	}

		b.uint32(1)           // total number of disks

		if _, err := w.cw.Write(buf[:]); err != nil {
			return err
		}

		// store max values in the regular end record to signal
		// that the zip64 values should be used instead
		records = uint16max
		size = uint32max
		offset = uint32max
	}

	// write end record
	var buf [directoryEndLen]byte
	b := writeBuf(buf[:])

		},
		ok: false,
	}, {
		in: map[string]string{
			"missing":          "missing",
			"SCHILY.xattr.key": "value",
		},
		want: &Header{
			Xattrs: map[string]string{"key": "value"},
			PAXRecords: map[string]string{
				"missing":          "missing",
				"SCHILY.xattr.key": "value",
			},
		},
		ok: true,
	}}

	for i, v := range vectors {
		got := new(Header)

			if 'A' <= sr && sr <= 'Z' && tr == sr+'a'-'A' {
				continue
			}
			return false
		}

		// General case. SimpleFold(x) returns the next equivalent rune > x
		// or wraps around to smaller values.
		r := unicode.SimpleFold(sr)
		for r != sr && r < tr {
			r = unicode.SimpleFold(r)
		}
		if r == tr {
			continue
		}
		return false
	}

	// One string is empty. Are both?