code: func MarshalResponse(id interface{}, result interface{}, rpcErr *RPCError) ([]byte, error) {
  	marshalledResult, err := json.Marshal(result)
  	if err != nil {
  		return nil, err
  	}
  	response, err := NewResponse(id, marshalledResult, rpcErr)
  	if err != nil {
  		return nil, err
  	}
  	return json.Marshal(&response)
  }
docs: // MarshalResponse marshals the passed id, result, and RPCError to a JSON-RPC
  // response byte slice that is suitable for transmission to a JSON-RPC client.