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 _genSeq(self):
        self.raw_sequence = random.getrandbits(64)
        parts = []
        while self.raw_sequence:
            parts.append(self.raw_sequence & limit)
            self.raw_sequence >>= 32

        self.sequence = struct.pack('<' + 'L'*len(parts), *parts)
        # struct.unpack('<LL', '\xb1l\x1c\xb1\x11"\x10\xf4')
        return 0