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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def list(self, page=None, per_page=None, order_by='created_at', order_dir='DESC', service='facebook'):
 """ List pylon recordings :param page: page number for pagination :type page: int :param per_page: number of items per page, default 20 :type per_page: int :param order_by: field to order by, default request_time :type order_by: str :param order_dir: direction to order by, asc or desc, default desc :type order_dir: str :param service: The service for this API call (facebook, etc) :type service: str :return: dict of REST API output with headers attached :rtype: :class:`~datasift.request.DictResponse` :raises: :class:`~datasift.exceptions.DataSiftApiException`, :class:`requests.exceptions.HTTPError` """


        params = {}

        if page:
            params['page'] = page
        if per_page:
            params['per_page'] = per_page
        if order_by:
            params['order_by'] = order_by
        if order_dir:
            params['order_dir'] = order_dir

        return self.request.get(service + '/get', params)