code: func (d *Dispatcher) NewFuncClient(c *Client) *DispatcherClient {
  	if len(d.serviceMap) == 0 || d.serviceMap[""] == nil {
  		logPanic("gorpc.Dispatcher: register at least one function with AddFunc() before calling NewFuncClient()")
  	}
  
  	return &DispatcherClient{
  		c: c,
  	}
  }
docs: // NewFuncClient returns a client suitable for calling functions registered
  // via AddFunc().