code: def get(self, key, delete_if_expired=True):
          
          self._update_cache_stats(key, None)
  
          if key in self._CACHE:
              (expiration, obj) = self._CACHE[key]
              if expiration > self._now():
                  self._update_cache_stats(key, 'hit')
                  return obj
              else:
                  if delete_if_expired:
                      self.delete(key)
                      self._update_cache_stats(key, 'expired')
                      return None
      
          self._update_cache_stats(key, 'miss')
          return None
docs: Retrieve key from Cache.
  
          :param key: key to look up in cache.
          :type key: ``object``
  
          :param delete_if_expired: remove value from cache if it is expired.
                                    Default is True.
          :type delete_if_expired: ``bool``
  
          :returns: value from cache or None
          :rtype: varies or None