code: func (mx *Mux) Use(middlewares ...func(http.Handler) http.Handler) {
  	if mx.handler != nil {
  		panic("chi: all middlewares must be defined before routes on a mux")
  	}
  	mx.middlewares = append(mx.middlewares, middlewares...)
  }
docs: // Use appends a middleware handler to the Mux middleware stack.
  //
  // The middleware stack for any Mux will execute before searching for a matching
  // route to a specific handler, which provides opportunity to respond early,
  // change the course of the request execution, or set request-scoped values for
  // the next http.Handler.