def elapsed(self) -> Optional[float]:
        """Optional[float]: Time elapsed since task was started, or ``None`` if the task hasn't started."""
        if self.start_time is None:
            return None
        if self.stop_time is not None:
            return self.stop_time - self.start_time
        return self.get_time() - self.start_time
Optional[float]: Time elapsed since task was started, or ``None`` if the task hasn't started.
rich/progress.py