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):
        """Decides whether a directory should be visited based on whether it
        has potential matches in it or one of its subdirectories. This is
        based on the match's primary, included, and excluded patterns.

        Returns the string 'all' if the given directory and all subdirectories
        should be visited. Otherwise returns True or False indicating whether
        the given directory should be visited.
        """
        return True