code: func Shell(client *SSHForwardingClient) error {
  	session, finalize, err := makeSession(client)
  	if err != nil {
  		return err
  	}
  
  	defer finalize()
  
  	if err = session.Shell(); err != nil {
  		return err
  	}
  
  	session.Wait()
  	return nil
  }
docs: // Shell launches an interactive shell on the given client. It returns any
  // error encountered in setting up the SSH session.