def insert(self, doc, synced=False):
        doc.id = self.get_next_id()
        doc.synced = synced
        try:
            self.db.docs.insert(doc)
        except Exception as e:
            raise DatabaseException(e)
        return doc
def _restore_vars(v_list, t_list):
  """Restore variables in v_list from t_list."""
  ops = []
  for v, t in zip(v_list, t_list):
    ops.append(v.assign(t))
  return ops