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 _getProvenanceAfterMetadata(self, item, meta, user):
        resp = self.request(path='/item/%s/metadata' % item['_id'],
                            method='PUT', user=user, body=json.dumps(meta),
                            type='application/json')
        self.assertStatusOk(resp)
        return self._getProvenance(item, user)