def _check_completed_futures(self):
        """Fail safe in this case means fail fast. TODO: Add retry logic"""
        for future in self._futures.copy():
            if future.done():
                # Will throw an exception here if the future failed
                future.result()
                self._futures.remove(future)
Fail safe in this case means fail fast. TODO: Add retry logic
ethereumetl/executors/fail_safe_executor.py