code: func (s *SessionStore) GetSession(c context.Context, sessionID string) (*auth.Session, error) {
  	c = defaultNS(c)
  	ent, err := s.fetchSession(c, sessionID)
  	if ent == nil {
  		return nil, err
  	}
  	return &auth.Session{
  		SessionID: sessionID,
  		UserID:    ent.Parent.StringID()[len(s.Prefix)+1:],
  		User: auth.User{
  			Identity:  identity.Identity(ent.Profile.Identity),
  			Superuser: ent.Profile.Superuser,
  			Email:     ent.Profile.Email,
  			Name:      ent.Profile.Name,
  			Picture:   ent.Profile.Picture,
  		},
  		Exp: ent.Expiration,
  	}, nil
  }
docs: // GetSession returns existing non-expired session given its ID. Returns nil
  // if session doesn't exist, closed or expired. Returns only transient errors.