code: func NewClient(conn ble.Conn) (*Client, error) {
  	p := &Client{
  		subs: make(map[uint16]*sub),
  		conn: conn,
  	}
  	p.ac = att.NewClient(conn, p)
  	go p.ac.Loop()
  	return p, nil
  }
docs: // NewClient returns a GATT Client.