def elapsed(self, since_last_check=False):
        if since_last_check:
            window_start = self.last_check
        else:
            window_start = self.start

        current_datetime = datetime.datetime.now()
        self.last_check = current_datetime

        elapsed_seconds = (window_start - current_datetime).total_seconds()
        return elapsed_seconds
dataset/ETHPy150Open Impactstory/total-impact-webapp/util.py/Timer.elapsed/swapped operands of `-`