def get(self, uid: int) -> FrozenSet[Flag]:
        """Return the session flags for the mailbox session.

        Args:
            uid: The message UID value.

        """
        recent = _recent_set if uid in self._recent else frozenset()
        flags = self._flags.get(uid)
        return recent if flags is None else (flags | recent)
Return the session flags for the mailbox session.

        Args:
            uid: The message UID value.