def post_work_result(self, function_arn, work_item):
        """
        Post the result of processing work item by :code:`function_arn`.

        :param function_arn: Arn of the Lambda function intended to receive the work for processing.
        :type function_arn: string

        :param work_item: The WorkItem holding the results of the work being posted.
        :type work_item: WorkItem

        :returns: None
        """
        url = self._get_work_url(function_arn)

        runtime_logger.info('Posting work result for invocation id [{}] to {}'.format(work_item.invocation_id, url))
        request = Request(url, work_item.payload or b'')

        request.add_header(HEADER_INVOCATION_ID, work_item.invocation_id)
        request.add_header(HEADER_AUTH_TOKEN, self.auth_token)

        urlopen(request)

        runtime_logger.info('Posted work result for invocation id [{}]'.format(work_item.invocation_id))