code: def _cache(self, response, key):
          
          # cache template and retrieval time for subsequent calls
          thetime = datetime.datetime.utcnow().replace(tzinfo=pytz.timezone("GMT"))
          self.templates[key] = {"tmplt": response.json(), "updated": thetime}
          return copy.deepcopy(response.json())
docs: Add a retrieved template to the cache for 304 checking
          accepts a dict and key name, adds the retrieval time, and adds both
          to self.templates as a new dict using the specified key