'Remove the timer from the IOLoop using the handle returned from
add_timeout.
param: timer instance handle'

def remove_timeout(self, timer):

    LOGGER.debug('stop')
    try:
        self._active_timers.pop(timer)
    except KeyError:
        LOGGER.warning('Attempted    to    remove    inactive    timer    %s', timer)
    else:
        timer.stop()
        self._stopped_timers.append(timer)
