Function standing 

pub fn standing(
    grant: &Grant,
    ceiling: &dyn ScopePolicy,
    admission: &dyn TokenAdmission,
) -> Standing

Judges one live grant the way POST /oauth/token would judge it if the client presented its refresh token right now.

A grant whose stored client_id no longer parses may do nothing and is not admitted, which is the same answer every other reader of a stored client id gets; see stored_client_id.