diff --git a/examples/distillation/lm_seqs_dataset.py b/examples/distillation/lm_seqs_dataset.py
index a29e9efb28..8f444f4e0e 100644
--- a/examples/distillation/lm_seqs_dataset.py
+++ b/examples/distillation/lm_seqs_dataset.py
@@ -114,17 +114,17 @@ class LmSeqsDataset(Dataset):
         """
         Remove sequences with a (too) high level of unknown tokens.
         """
-        if 'unk_token' not in self.params.special_tok_ids:
+        if "unk_token" not in self.params.special_tok_ids:
             return
         else:
-            unk_token_id = self.params.special_tok_ids['unk_token']
+            unk_token_id = self.params.special_tok_ids["unk_token"]
         init_size = len(self)
         unk_occs = np.array([np.count_nonzero(a == unk_token_id) for a in self.token_ids])
-        indices = (unk_occs/self.lengths) < 0.5
+        indices = (unk_occs / self.lengths) < 0.5
         self.token_ids = self.token_ids[indices]
         self.lengths = self.lengths[indices]
         new_size = len(self)
-        logger.info(f'Remove {init_size - new_size} sequences with a high level of unknown tokens (50%).')
+        logger.info(f"Remove {init_size - new_size} sequences with a high level of unknown tokens (50%).")
 
     def print_statistics(self):
         """