code: func (cln *Client) DiscoverIncludedServices(ss []ble.UUID, s *ble.Service) ([]*ble.Service, error) {
  	rsp := cln.conn.sendReq(60, xpc.Dict{
  		"kCBMsgArgDeviceUUID":         cln.id,
  		"kCBMsgArgServiceStartHandle": s.Handle,
  		"kCBMsgArgServiceEndHandle":   s.EndHandle,
  		"kCBMsgArgUUIDs":              uuidSlice(ss),
  	})
  	if rsp.err() != nil {
  		return nil, rsp.err()
  	}
  	return nil, ble.ErrNotImplemented
  }
docs: // DiscoverIncludedServices finds the included services of a service. [Vol 3, Part G, 4.5.1]
  // If filter is specified, only filtered services are returned.