Start the recurring task.

def run(self):
        """Start the recurring task."""
        if self.init_sec:
            sleep(self.init_sec)
        self._functime = time()
        while self._running:
            start = time()
            self._func()
            self._functime += self.interval_sec
            if self._functime - start > 0:
                sleep(self._functime - start)