diff --git a/egs/wenetspeech/ASR/transducer_stateless/model.py b/egs/wenetspeech/ASR/transducer_stateless/model.py
index 46050e5ab..9f9455bdd 100644
--- a/egs/wenetspeech/ASR/transducer_stateless/model.py
+++ b/egs/wenetspeech/ASR/transducer_stateless/model.py
@@ -107,13 +107,16 @@ class Transducer(nn.Module):
         max_sym_id = torch.max(y_padded)
         assert encoder_out.size(0) == decoder_out.size(0), [
             encoder_out.size(),
-            decoder_out.size()]
+            decoder_out.size(),
+        ]
         assert encoder_out.size(2) == decoder_out.size(2), [
             encoder_out.size(),
-            decoder_out.size()]
+            decoder_out.size(),
+        ]
         assert encoder_out.size(2) >= (max_sym_id + 1), [
             encoder_out.size(),
-            max_sym_id]
+            max_sym_id,
+        ]
 
         boundary = torch.zeros(
             (x.size(0), 4), dtype=torch.int64, device=x.device