code: func (mux *ServeMux) ServeDHCP(w ResponseSender, r *Request) {
  	mux.mu.RLock()
  	defer mux.mu.RUnlock()
  	h, ok := mux.m[r.MessageType]
  	if !ok {
  		return
  	}
  
  	h.ServeDHCP(w, r)
  }
docs: // ServeDHCP implements Handler for ServeMux, and serves a DHCP request using
  // the appropriate handler for an input Request's MessageType.  If the
  // MessageType does not match a valid Handler, ServeDHCP does not invoke any
  // handlers, ignoring a client's request.