code: func (s *Server) handleWriteCommand(r WriteCommand) []byte {
  	// Validate the request.
  	switch {
  	case len(r) <= 3:
  		return nil
  	}
  
  	a, ok := s.db.at(r.AttributeHandle())
  	if !ok {
  		return nil
  	}
  
  	// We don't support write to static value. Pass the request to upper layer.
  	if a == nil {
  		return nil
  	}
  	if e := handleATT(a, s.conn, r, s.dummyRspWriter); e != ble.ErrSuccess {
  		return nil
  	}
  	return nil
  }
docs: // handle Write command. [Vol 3, Part F, 3.4.5.3]