code: func NewSessionService() *SessionService {
  	return &SessionService{
  		FindSessionFn:   func(context.Context, string) (*platform.Session, error) { return nil, fmt.Errorf("mock session") },
  		CreateSessionFn: func(context.Context, string) (*platform.Session, error) { return nil, fmt.Errorf("mock session") },
  		ExpireSessionFn: func(context.Context, string) error { return fmt.Errorf("mock session") },
  	}
  }
docs: // NewSessionService returns a mock SessionService where its methods will return
  // zero values.