//
	// To use AccessTime or ChangeTime, specify the Format as PAX or GNU.
	// To use sub-second resolution, specify the Format as PAX.
	ModTime    time.Time // Modification time
	AccessTime time.Time // Access time (requires either PAX or GNU support)
	ChangeTime time.Time // Change time (requires either PAX or GNU support)

	Devmajor int64 // Major device number (valid for TypeChar or TypeBlock)

			// atime and ctime fields (e.g., when they are valid octal strings),
			// then it is impossible to distinguish between a valid GNU file
			// and an invalid pre-Go1.8 file.
			//
			// See https://golang.org/issues/12594
			// See https://golang.org/issues/21005
			if p2.err != nil {
				hdr.AccessTime, hdr.ChangeTime = time.Time{}, time.Time{}
				ustar := tr.blk.toUSTAR()

				PAXRecords: map[string]string{"path": ""}, // Should delete "path", but keep "mtime"
			}, nil},
			testHeader{Header{
				Typeflag: TypeReg, Name: "file3",
			}, nil},
			testHeader{Header{
				Typeflag:   TypeReg,
				Name:       "file4",
				ModTime:    time.Unix(1400000000, 0),
				PAXRecords: map[string]string{"mtime": "1400000000"},
			}, nil},
			testClose{nil},
		},
	}, {

	}, {
		header:  &Header{ModTime: time.Unix(1, 500)},
		paxHdrs: map[string]string{paxMtime: "1.0000005"},
		formats: FormatUSTAR | FormatPAX | FormatGNU,
	}, {
		header:  &Header{ModTime: time.Unix(1, 0)},
		formats: FormatUSTAR | FormatPAX | FormatGNU,
	}, {
		header:  &Header{ModTime: time.Unix(1, 0), Format: FormatPAX},
		formats: FormatUSTAR | FormatPAX,
	}, {
		header:  &Header{ModTime: time.Unix(1, 500), Format: FormatUSTAR},

//
// Since the set of packages that exist depends on context, the result of
// loadImports also depends on context. However, to improve test running time
// the configuration for each environment is cached across runs.
func (w *Walker) loadImports() {
	if w.context == nil {
		return // test-only Walker; does not use the import map
	}

</p>

<p>
This program starts a goroutine for every entry in the work list, but the
goroutines coordinate using the <code>limit</code> channel to ensure
that at most three are running work functions at a time.
</p>

<pre>
var limit = make(chan int, 3)

func main() {
	for _, w := range work {
		go func(w func()) {
			limit &lt;- 1
			w()
			&lt;-limit
		}(w)
	}
	select{}
}

		// but at least most seem to be able to understand the other formats.
		//
		// This format happens to be identical for both local and central header
		// if modification time is the only timestamp being encoded.
		var mbuf [9]byte // 2*SizeOf(uint16) + SizeOf(uint8) + SizeOf(uint32)
		mt := uint32(fh.Modified.Unix())
		eb := writeBuf(mbuf[:])
		eb.uint16(extTimeExtraID)