type Client struct {
  cl *telegram.Client
  auth         auth.UserAuthenticator
  sendcodeOpts auth.SendCodeOptions
}

// func (c *Client) Run() error {
stop, err := bg.Connect(c.cl)
if err != nil {
  return err
}
defer func() {
  if err := stop(); err!=nil {
    log.Print(err)
  }
}()
// even if Run fails with error, we will reach this point


flow := auth.NewFlow(c.auth, c.sendcodeOpts)

// *** the following will hang indefinitely ***
if err := c.cl.Auth().IfNecessary(ctx, flow); err != nil {
  return err
}

log.Debug("auth success")

return nil
}