diff --git a/pytorch_lightning/loggers/comet.py b/pytorch_lightning/loggers/comet.py
index eaf18621c0ce4..7e146a2037dd9 100644
--- a/pytorch_lightning/loggers/comet.py
+++ b/pytorch_lightning/loggers/comet.py
@@ -166,7 +166,11 @@ def log_hyperparams(self, params: argparse.Namespace):
         self.experiment.log_parameters(vars(params))
 
     @rank_zero_only
-    def log_metrics(self, metrics: Dict[str, Union[torch.Tensor, float]], step: Optional[int] = None):
+    def log_metrics(
+            self,
+            metrics: Dict[str, Union[torch.Tensor, float]],
+            step: Optional[int] = None
+    ):
         # Comet.ml expects metrics to be a dictionary of detached tensors on CPU
         for key, val in metrics.items():
             if is_tensor(val):