code: def lookup(self, key):
      if self.dummy:
          return None
  
      if self.initialised == -1:
          self.initialise()
  
      if self.initialised == 0:  # failure
          return None
  
      try:
          return _KV.get(_KV.key == key).value
      except _KV.DoesNotExist:
          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 4 for calling the _TzCache obj's underlying member method code with example usage: obj.lookup(key) and returns: None, None, _KV, None