code: def namespace_token(self, ns: str) -> Optional[str]:
      return self._tokens.get(ns)
  
imports: from typing import Optional, Dict, Tuple
  import base64
  import collections.abc
  import os
  import json
  import logging
  from hailtop.config import get_deploy_config
  from hailtop.utils import first_extant_file
label_desc: Use image node_id 7 for calling the Tokens obj's underlying member method code with example usage: obj.namespace_token(ns) and returns: self