'Return list of children in requested library item.
Parameters required:    rating_key { ratingKey of parent }
Optional parameters:    output_format { dict, json }
Output: array'

def get_children_list(self, rating_key='', output_format=''):

    uri = (('/library/metadata/' + rating_key) + '/children')
    request = self.request_handler.make_request(uri=uri, proto=self.protocol, request_type='GET', output_format=output_format)
    return request
