':param _: The deferred which we ignore.
This function handles the scenario of the session prematurely being cleaned up,
most likely due to a shutdown.
This function only should be called by the result_deferred.'

def _on_cancel(self, a):

    self._logger.info('The    result    deferred    of    this    HTTP    tracker    session    is    being    cancelled    due    to    a    session    cleanup.    HTTP    url:    %s', self.tracker_url)
