class_docstr: TokenStore is a class for reading/updating a persistent store of user authentication tokens.
  TokenStore can remember tokens for many users for each of many masters.  It can also remembers
  one "active user" for each master, which is set via `det user login`.
  
  All updates to the file follow a read-modify-write pattern, and use file locks to protect the
  integrity of the underlying file cache.
class_docstr_tok: ["TokenStore","is","a","class","for","reading\/updating","a","persistent","store","of","user","authentication","tokens",".","TokenStore","can","remember","tokens","for","many","users","for","each","of","many","masters",".","It","can","also","remembers","one","``","active","user","''","for","each","master",",","which","is","set","via","`","det","user","login","`",".","All","updates","to","the","file","follow","a","read-modify-write","pattern",",","and","use","file","locks","to","protect","the","integrity","of","the","underlying","file","cache","."]
code: def drop_user(self, username: str) -> None:
      with self._persistent_store() as substore:
          tokens = substore.setdefault("tokens", {})
          if username in tokens:
              del tokens[username]
  
imports: import argparse
  import contextlib
  import functools
  import getpass
  import hashlib
  import json
  import pathlib
  from typing import Any, Callable, Dict, Iterator, List, NamedTuple, Optional, Tuple, cast
  import filelock
  import determined
  from determined.common import api, constants, util
  from determined.common.api import bindings, certs
label_desc: Use image node_id 7 for calling the TokenStore obj's underlying member method code with example usage: obj.drop_user(username) without return types