def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def exiter_as(cls, new_exiter_fun: Callable[[Optional[Exiter]], Exiter]) -> Iterator[None]:
        """Temporarily override the global exiter.

        NB: We don't want to try/finally here, because we want exceptions to propagate
        with the most recent exiter installed in sys.excepthook.
        If we wrap this in a try:finally, exceptions will be caught and exiters unset.
        """
        previous_exiter = cls._exiter
        new_exiter = new_exiter_fun(previous_exiter)
        cls._reset_exiter(new_exiter)
        yield
        cls._reset_exiter(previous_exiter)