From 688f75295665f8babbfdfc228e4bc554a8ba32b8 Mon Sep 17 00:00:00 2001
From: Caroline Chen <carolinechen@fb.com>
Date: Thu, 10 Mar 2022 15:31:57 -0800
Subject: [PATCH] Fix type for lm parameter in decoder (#2273)

Summary: Pull Request resolved: https://github.com/pytorch/audio/pull/2273

Reviewed By: mthrok

Differential Revision: D34799335

Pulled By: carolineechen

fbshipit-source-id: d0eea79448efdbd84758a3f433ab9350b4c94e91
---
 torchaudio/prototype/ctc_decoder/ctc_decoder.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/torchaudio/prototype/ctc_decoder/ctc_decoder.py b/torchaudio/prototype/ctc_decoder/ctc_decoder.py
index 3c0bf1883d..567dcbe659 100644
--- a/torchaudio/prototype/ctc_decoder/ctc_decoder.py
+++ b/torchaudio/prototype/ctc_decoder/ctc_decoder.py
@@ -181,7 +181,7 @@ def idxs_to_tokens(self, idxs: torch.LongTensor) -> List:
 def lexicon_decoder(
     lexicon: str,
     tokens: Union[str, List[str]],
-    lm: str = None,
+    lm: Optional[str] = None,
     nbest: int = 1,
     beam_size: int = 50,
     beam_size_token: Optional[int] = None,