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 __getitem__(self, key):
        value = self._collection[key]
        if isinstance(key, slice):
            slice_repr = ":".join(str("" if i is None else i) for i in (key.start, key.stop, key.step))
            logger.debug("Get /%s[%s] config key", "/".join(self._path), slice_repr)
            return [self._to_python(item) for item in value]
        else:
            logger.debug("Get /%s[%s] config key", "/".join(self._path), key)
            return self._to_python(value)