'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.'

def batch_get_item(self, request_items, object_hook=None):

    if (not request_items):
        return {}
    data = {'RequestItems': request_items}
    json_input = json.dumps(data)
    return self.make_request('BatchGetItem', json_input, object_hook=object_hook)
