code: def __call__(self, **kwargs):
      if self._key is None:
          self._key = self.retrieve_key(**kwargs)
      return self._key
  
imports: import os
  import re
  import requests
label_desc: Use image node_id 2 for calling the CanadapostKeyLazySingleton obj's underlying member method code with example usage: obj.__call__() and returns: self