}
		strs = make([]string, hint)
	}

	m := make(MIMEHeader, hint)

	// Account for 400 bytes of overhead for the MIMEHeader, plus 200 bytes per entry.
	// Benchmarking map creation as of go1.20, a one-entry MIMEHeader is 416 bytes and large
	// MIMEHeaders average about 200 bytes per entry.
	maxMemory -= 400
	const mapEntryOverhead = 200

	var buf strings.Builder
	w := NewWriter(&buf)
	if err := w.SetBoundary("MIMEBOUNDARY"); err != nil {
		t.Fatalf("Error setting mime boundary: %v", err)
	}

	header := textproto.MIMEHeader{
		"A": {"2"},
		"B": {"5", "7", "6"},
		"C": {"4"},
		"M": {"3"},
		"Z": {"1"},
	}

	part, err := w.CreatePart(header)
	if err != nil {
		t.Fatalf("Unable to create part: %v", err)
	}

}

func (r httpRange) contentRange(size int64) string {
	return fmt.Sprintf("bytes %d-%d/%d", r.start, r.start+r.length-1, size)
}

func (r httpRange) mimeHeader(contentType string, size int64) textproto.MIMEHeader {
	return textproto.MIMEHeader{
		"Content-Range": {r.contentRange(size)},
		"Content-Type":  {contentType},
	}
}

// parseRange parses a Range header string as per RFC 7233.

		},
	}

	// Validate if the extracting headers.
	for i, testCase := range testCases {
		metadata := make(map[string]string)
		err := extractMetadataFromMime(context.Background(), textproto.MIMEHeader(testCase.header), metadata)
		if err != nil && !testCase.shouldFail {
			t.Fatalf("Test %d failed to extract metadata: %v", i+1, err)
		}
		if err == nil && testCase.shouldFail {

		return nil, badStringError("malformed HTTP version", resp.Proto)
	}

	// Parse the response headers.
	mimeHeader, err := tp.ReadMIMEHeader()
	if err != nil {
		if err == io.EOF {
			err = io.ErrUnexpectedEOF
		}
		return nil, err
	}
	resp.Header = Header(mimeHeader)

	fixPragmaCacheControl(resp.Header)

	err = readTransfer(resp, r)
	if err != nil {
		return nil, err
	}

			name := strings.Repeat("a", 10<<20)
			w, _ := fw.CreateFormField(name)
			w.Write([]byte("value"))
		},
	}, {
		name: "large MIME header",
		f: func(fw *Writer) {
			h := make(textproto.MIMEHeader)
			h.Set("Content-Disposition", `form-data; name="a"`)
			h.Set("X-Foo", strings.Repeat("a", 10<<20))
			w, _ := fw.CreatePart(h)
			w.Write([]byte("value"))
		},
	}, {
		name: "many parts",

	// for "100 Continue" responses, even if Got100Continue is also defined.
	// If it returns an error, the client request is aborted with that error value.
	Got1xxResponse func(code int, header textproto.MIMEHeader) error

	// DNSStart is called when a DNS lookup begins.
	DNSStart func(DNSStartInfo)

	// DNSDone is called when a DNS lookup ends.
	DNSDone func(DNSDoneInfo)

type Part struct {
	// The headers of the body, if any, with the keys canonicalized
	// in the same fashion that the Go http.Request headers are.
	// For example, "foo-bar" changes case to "Foo-Bar"
	Header textproto.MIMEHeader

	mr *Reader

	disposition       string
	dispositionParams map[string]string

	// r is either a reader directly reading from mr, or it's a
	// wrapper around such a reader, decoding the

		t.Helper()

		for _, h := range []string{"Content-Length", "Transfer-Encoding"} {
			if v, ok := header[h]; ok {
				t.Errorf("%s is %q; must not be sent", h, v)
			}
		}
	}

	var respCounter uint8
	trace := &httptrace.ClientTrace{
		Got1xxResponse: func(code int, header textproto.MIMEHeader) error {
			switch respCounter {
			case 0:

// If there are no values associated with the key, Get returns "".
// To access multiple values of a key, or to use non-canonical keys,
// access the map directly.
func (h Header) Get(key string) string {
	return textproto.MIMEHeader(h).Get(key)
}

var ErrHeaderNotPresent = errors.New("mail: header not in message")

// Date parses the Date header field.
func (h Header) Date() (time.Time, error) {
	hdr := h.Get("Date")
	if hdr == "" {