textproto.MIMEHeader(h).Del(key)
}

// Write writes a header in wire format.
func (h Header) Write(w io.Writer) error {
	return h.write(w, nil)
}

func (h Header) write(w io.Writer, trace *httptrace.ClientTrace) error {
	return h.writeSubset(w, nil, trace)
}

// Clone returns a copy of h or nil if h is nil.
func (h Header) Clone() Header {
	if h == nil {
		return nil
	}

	// Find total number of values.

	}
	dt.roundTripCount++
	dt.t.Logf("RoundTrip %v: started", rt.roundTripID)
	dt.t.Cleanup(func() {
		rt.cancel()
		rt.finish()
	})
	go func() {
		ctx = httptrace.WithClientTrace(ctx, &httptrace.ClientTrace{
			GotConn: func(info httptrace.GotConnInfo) {
				rt.conn = info.Conn.(*transportDialTesterConn)
			},
		})
		req, _ := http.NewRequestWithContext(ctx, "POST", dt.cst.ts.URL, pr)