Fix codestyle

lighter/system.py

@@ -205,9 +205,12 @@ def _base_step(self, batch: Dict, batch_idx: int, mode: str) -> Union[Dict[str,
         target = apply_fns(target, self.postprocessing["logging"]["target"])
         pred = apply_fns(pred, self.postprocessing["logging"]["pred"])
 
-        # If the loss is a dict, the sublosses must be combined under "total" key.
+        # Ensure that a dict of losses has a 'total' key.
         if isinstance(loss, dict) and "total" not in loss:
-            raise ValueError("The loss dictionary must include a 'total' key that combines all sublosses. Example: {'total': combined_loss, 'subloss1': loss1, ...}")
+            raise ValueError(
+                "The loss dictionary must include a 'total' key that combines all sublosses. "
+                "Example: {'total': combined_loss, 'subloss1': loss1, ...}"
+            )
 
         # Logging
         self._log_stats(loss, metrics, mode, batch_idx)