None roles are stored as empty strings, so the role returned as None
        by this function means that corresponding DID is not stored in a ledger.

def get_role(self, request: Request):
        """
        None roles are stored as empty strings, so the role returned as None
        by this function means that corresponding DID is not stored in a ledger.
        """
        idr = request.identifier
        return self._get_role(idr)