sse python demo modification

def _hello_world_aggr(request, context):
        """
        Aggregates the parameters to a single comma separated string.
        :param request: iterable sequence of bundled rows
        :return: string
        """
        params = []
        logging.info('hello_world_aggr called')
        # Iterate over bundled rows
        for request_rows in request:
            # Iterate over rows
            for row in request_rows.rows:
                # Retrieve string value of parameter and append to the params variable
                # Length of param is 1 since one column is received, the [0] collects the first value in the list
                param = [d.strData for d in row.duals][0]
                params.append(param)

        # Aggregate parameters to a single string
        result = ', '.join(params)
        logging.info('writing members to file')
        file = open("members.txt","w")
        file.write(result)
        file.close()
        logging.info('done')
        result = 'ok'
        # Create an iterable of dual with the result
        duals = iter([SSE.Dual(strData=result)])

        # Yield the row data as bundled rows
        yield SSE.BundledRows(rows=[SSE.Row(duals=duals)])