'Get time until the script fires it `at_repeat` hook again.
Returns:
next (int): Time in seconds until the script runs again.
If not a timed script, return `None`.
Notes:
This hook is not used in any way by the script\'s stepping
system; it\'s only here for the user to be able to check in
on their scripts and when they will next be run.'

def time_until_next_repeat(self):

    task = self.ndb._task
    if task:
        try:
            return int(round(task.next_call_time()))
        except TypeError:
            pass
    return None
