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 visitdir(self, dir):
        m1dir = self.m1.visitdir(dir)
        m2dir = self.m2.visitdir(dir)

        # if both matchers return "all" then we know for sure we don't need
        # to visit this directory. Same if all matchers return False. In all
        # other case we have to visit a directory.
        if m1dir == "all" and m2dir == "all":
            return False
        if not m1dir and not m2dir:
            return False
        return True