code: func (mx *Mux) MethodNotAllowedHandler() http.HandlerFunc {
  	if mx.methodNotAllowedHandler != nil {
  		return mx.methodNotAllowedHandler
  	}
  	return methodNotAllowedHandler
  }
docs: // MethodNotAllowedHandler returns the default Mux 405 responder whenever
  // a method cannot be resolved for a route.