code: def batch_get_item(self, request_items, object_hook=None):
          
          data = {'RequestItems' : request_items}
          json_input = json.dumps(data)
          return self.make_request('BatchGetItem', json_input,
                                   object_hook=object_hook)
docs: Return a set of attributes for a multiple items in
          multiple tables using their primary keys.
  
          :type request_items: dict
          :param request_items: A Python version of the RequestItems
              data structure defined by DynamoDB.