code: func NewClient(l2c ble.Conn, h NotificationHandler) *Client {
  	c := &Client{
  		l2c:     l2c,
  		rspc:    make(chan []byte),
  		chTxBuf: make(chan []byte, 1),
  		rxBuf:   make([]byte, ble.MaxMTU),
  		chErr:   make(chan error, 1),
  		handler: h,
  	}
  	c.chTxBuf <- make([]byte, l2c.TxMTU(), l2c.TxMTU())
  	return c
  }
docs: // NewClient returns an Attribute Protocol Client.