ErrNotImplemented     = errors.New("function not implemented")
	ErrAccessTokenExpired = errors.New("access_token expired or unauthorized")
)

// Provider implements identity provider specific admin operations, such as
// looking up users, fetching additional attributes etc.
type Provider interface {
	LoginWithUser(username, password string) error
	LoginWithClientID(clientID, clientSecret string) error
	LookupUser(userid string) (User, error)