class_docstr: Dummy cache to use if tz cache is disabled
class_docstr_tok: ["Dummy","cache","to","use","if","tz","cache","is","disabled"]
code: def lookup(self, tkr):
      return None
  
imports: import peewee
  from threading import Lock
  import os
  import appdirs
  import atexit
  import datetime
  import pickle
  from .utils import get_yf_logger
label_desc: Use image node_id 1 for calling the _TzCacheDummy obj's underlying member method code with example usage: obj.lookup(tkr) and returns: None