func crawlLoop() {
	for url := range urlq {
		if err := doCrawl(url); err != nil {
			addProblem(url, err.Error())
		}
	}
}

func doCrawl(url string) error {
	defer wg.Done()

	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		return err
	}
	res, err := http.DefaultTransport.RoundTrip(req)
	if err != nil {
		return err
	}
	// Handle redirects.
	if res.StatusCode/100 == 3 {

pkg net/http, var ErrUseLastResponse error
pkg net/http, var LocalAddrContextKey *contextKey
pkg net/http, var ServerContextKey *contextKey
pkg net/http/cgi, type Handler struct, Stderr io.Writer
pkg net/http/httptest, func NewRequest(string, string, io.Reader) *http.Request
pkg net/http/httptest, method (*ResponseRecorder) Result() *http.Response
pkg net/http/httptrace, func ContextClientTrace(context.Context) *ClientTrace

pkg net/http, func MaxBytesReader(ResponseWriter, io.ReadCloser, int64) io.ReadCloser
pkg net/http, func NewFileTransport(FileSystem) RoundTripper
pkg net/http, func NewRequest(string, string, io.Reader) (*Request, error)
pkg net/http, func NewServeMux() *ServeMux
pkg net/http, func NotFound(ResponseWriter, *Request)
pkg net/http, func NotFoundHandler() Handler