docs: def unpickle_dict(items):
      '''Returns a dict pickled with pickle_dict'''
      pickled_keys = items.pop('_pickled', '').split(',')
      ret = {}
      for key, val in items.items():
          if key in pickled_keys:
              ret[key] = pickle.loads(val)
          else:
              ret[key] = val
      return ret