code: func RegexPath(reg *regexp.Regexp, h http.Handler) http.Handler {
  	if reg == nil {
  		return h
  	}
  
  	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  		matches := reg.FindStringSubmatch(r.URL.Path)
  		if len(matches) > 1 {
  			r.URL.Path = matches[1]
  			h.ServeHTTP(w, r)
  		} else {
  			http.NotFound(w, r)
  		}
  	})
  }
docs: // RegexPath returns a handler that serves HTTP requests
  // with the first match of the the given regex from the request URL's Path
  // and invoking the handler h. RegexPath handles a
  // request for a path that doesn't match by
  // replying with an HTTP 404 not found error.