func removeHopByHopHeaders(h http.Header) {
	// RFC 7230, section 6.1: Remove headers listed in the "Connection" header.
	for _, f := range h["Connection"] {
		for _, sf := range strings.Split(f, ",") {
			if sf = textproto.TrimString(sf); sf != "" {
				h.Del(sf)
			}
		}
	}
	// RFC 2616, section 13.5.1: Remove a set of known hop-by-hop headers.
	// This behavior is superseded by the RFC 7230 Connection header, but

	userAgent := defaultUserAgent
	if r.Header.has("User-Agent") {
		userAgent = r.Header.Get("User-Agent")
	}
	if userAgent != "" {
		userAgent = headerNewlineToSpace.Replace(userAgent)
		userAgent = textproto.TrimString(userAgent)
		_, err = fmt.Fprintf(w, "User-Agent: %s\r\n", userAgent)
		if err != nil {
			return err
		}
		if trace != nil && trace.WroteHeaderField != nil {

func foreachHeaderElement(v string, fn func(string)) {
	v = textproto.TrimString(v)
	if v == "" {
		return
	}
	if !strings.Contains(v, ",") {
		fn(v)
		return
	}
	for _, f := range strings.Split(v, ",") {
		if f = textproto.TrimString(f); f != "" {
			fn(f)
		}
	}
}

func http2foreachHeaderElement(v string, fn func(string)) {
	v = textproto.TrimString(v)
	if v == "" {
		return
	}
	if !strings.Contains(v, ",") {
		fn(v)
		return
	}
	for _, f := range strings.Split(v, ",") {
		if f = textproto.TrimString(f); f != "" {
			fn(f)
		}
	}
}

// From http://httpwg.org/specs/rfc7540.html#rfc.section.8.1.2.2

		{"NewReader", Func, 0},
		{"NewWriter", Func, 0},
		{"Pipeline", Type, 0},
		{"ProtocolError", Type, 0},
		{"Reader", Type, 0},
		{"Reader.R", Field, 0},
		{"TrimBytes", Func, 1},
		{"TrimString", Func, 1},
		{"Writer", Type, 0},
		{"Writer.W", Field, 0},
	},
	"net/url": {
		{"(*Error).Error", Method, 0},
		{"(*Error).Temporary", Method, 6},
		{"(*Error).Timeout", Method, 6},

pkg net/rpc, const DefaultDebugPath = "/debug/rpc"
pkg net/rpc, const DefaultRPCPath = "/_goRPC_"
pkg net/smtp, method (*Client) Hello(string) error
pkg net/textproto, func TrimBytes([]uint8) []uint8
pkg net/textproto, func TrimString(string) string
pkg os (darwin-386), const DevNull = "/dev/null"
pkg os (darwin-386), const O_APPEND = 8
pkg os (darwin-386), const O_CREATE = 512
pkg os (darwin-386), const O_EXCL = 2048