code: func (ph *permissionHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
  	// Check if the user has the right admin/user rights
  	if ph.perm.Rejected(w, req) {
  		// Let the user know, by calling the custom "permission denied" function
  		ph.perm.DenyFunction()(w, req)
  		// Reject the request by not calling the next handler below
  		return
  	}
  	// Serve the requested page if permissions were granted
  	ph.mux.ServeHTTP(w, req)
  }
docs: // Implement the ServeHTTP method to make a permissionHandler a http.Handler