code: func (s *Streamer) SendJSON(id, event string, v interface{}) error {
  	data, err := json.Marshal(v)
  	if err != nil {
  		return err
  	}
  	p := format(id, event, len(data))
  	copy(p[len(p)-(2+len(data)):], data) // fill in data
  	s.event <- p
  	return nil
  }
docs: // SendJSON sends an event with the given data encoded as JSON to all connected
  // clients.
  // If the id or event string is empty, no id / event type is send.