'Run Gratipay\'s weekly payday.
If there is a Payday that hasn\'t finished yet, then the UNIQUE
constraint on ts_end will kick in and notify us of that. In that case
we load the existing Payday and work on it some more. We use the start
time of the current Payday to synchronize our work.'

def run_payday(self):

    self._start_payday().run()
