Function client_id_superseded 

pub fn client_id_superseded(
    discovered: Option<&CloudSettings>,
    stored_client_id: &str,
) -> bool

Was a stored sign-in issued to a Cognito client the cloud no longer publishes? Then it belongs to a user pool the cloud has left, and neither its tokens nor a refresh will work. false when that can’t be told: no document, or a credential saved without its client id.