func getContentChecksum(h http.Header) (t ChecksumType, s string) {
	t = ChecksumNone
	alg := h.Get(xhttp.AmzChecksumAlgo)
	if alg != "" {
		t |= NewChecksumType(alg)
		if t.IsSet() {
			hdr := t.Key()
			if s = h.Get(hdr); s == "" {
				return ChecksumNone, ""
			}
		}
		return t, s
	}
	checkType := func(c ChecksumType) {
		if got := h.Get(c.Key()); got != "" {
			// If already set, invalid

		}) {
			t.Errorf("Contents not sorted")
		}
		for i := range xl.versions {
			hdr := xl.versions[i].header
			ver, err := xl.getIdx(i)
			if err != nil {
				t.Error(err)
				continue
			}
			gotHdr := ver.header()
			if hdr != gotHdr {
				t.Errorf("Header does not match, index: %+v != meta: %+v", hdr, gotHdr)
			}
		}
	}
	t.Run("load-legacy", func(t *testing.T) {
		var xl xlMetaV2

together. The directive can include a list of build constraints limiting its
effect to systems satisfying one of the constraints
(see https://golang.org/pkg/go/build/#hdr-Build_Constraints for details about the constraint syntax).
For example:

	// #cgo CFLAGS: -DPNG_DEBUG=1
	// #cgo amd64 386 CFLAGS: -DX86=1
	// #cgo LDFLAGS: -lpng
	// #include <png.h>
	import "C"

				"text/vnd.trolltech.linguist",
				"text/vnd.wap.si",
				"text/vnd.wap.sl",
				"text/vnd.wap.wml",
				"text/vnd.wap.wmlscript",
				"text/x-awk",
				"text/x-basic",
				"text/x-c++hdr",
				"text/x-c++src",
				"text/x-cgi",
				"text/x-chdr",
				"text/x-clojure",
				"text/x-coffeescript",
				"text/x-csrc",
				"text/x-csharp",
				"text/x-cobol",
				"text/x-coldfusion",

  <mime-type type="application/edi-x12"/>
  <mime-type type="application/edifact"/>
  <mime-type type="application/emma+xml">
    <glob pattern="*.emma"/>
  </mime-type>
  <mime-type type="application/envi.hdr">
    <glob pattern="*.hdr"/>
  </mime-type>
  <mime-type type="application/epp+xml"/>

  <mime-type type="application/epub+zip">
    <acronym>EPUB</acronym>
    <_comment>Electronic Publication</_comment>