code: func (h *Handle) MarshalJSON() ([]byte, error) {
  	m := map[string]interface{}{
  		"id": h.id,
  	}
  
  	b, err := h.ToByteArray()
  	if err != nil {
  		return nil, err
  	}
  	m["sequence"] = b
  	return json.Marshal(m)
  }
docs: // MarshalJSON encodes Handle into json message