Fails the transaction if Key is not currently locked by Session

        Parameters:
            key (str): Key to check
            session (ObjectID): Session ID

def check_session(self, key, *, session=None):
        """Fails the transaction if Key is not currently locked by Session

        Parameters:
            key (str): Key to check
            session (ObjectID): Session ID
        """
        self.append({
            "Verb": "check-session",
            "Key": key,
            "Session": extract_attr(session, keys=["ID"])
        })
        return self