class_docstr: CertStore represents a persistent file-based record of certificates, each associated with a
  particular master url.
docstr: get_cert returns the contents of a cert (if any) that has been associated with the given
  url.
docstr_tok: ["get_cert","returns","the","contents","of","a","cert","(","if","any",")","that","has","been","associated","with","the","given","url","."]
code: def get_cert(self, url: str) -> Optional[str]:
      """
      get_cert returns the contents of a cert (if any) that has been associated with the given
      url.
      """
      if not self.path.exists():
          return None
      # Technically this doesn't have to be modfiable, but it is unlikely to matter.
      with self._persistent_store() as store:
          return store.get(url)
  
imports: import atexit
  import contextlib
  import json
  import logging
  import os
  import pathlib
  import tempfile
  from typing import Dict, Iterator, Optional, Union, cast
  import certifi
  import filelock
  from determined.common import api, util
label_desc: Use image node_id 4 for calling the CertStore obj's underlying member method code with example usage: obj.get_cert(url) and returns: None, store