def _total_date_range(self):
        periods = self.all_periods()
        consumption_periods = [cd.total_period() for cd in self.consumption]
        periods += consumption_periods

        periods = [p for p in periods if p is not None]

        period_starts = [ p.start for p in periods]
        if None in period_starts:
            start_date = None
        else:
            start_date = min(period_starts)

        period_ends = [ p.end for p in periods]
        if None in period_ends:
            end_date = None
        else:
            end_date = max(period_ends)
        return start_date, end_date
dataset/ETHPy150Open impactlab/eemeter/eemeter/project.py/Project._total_date_range/original