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 display_name(self):
        """
        Find the most appropriate display name for a user: look for a "display_name", then
        a "real_name", and finally fall back to the always-present "name".
        """
        for k in self._NAME_KEYS:
            if self._raw.get(k):
                return self._raw[k]
            if "profile" in self._raw and self._raw["profile"].get(k):
                return self._raw["profile"][k]
        return self._raw["name"]