fix out of vocab token (#12)

- fix out of vocab token (59045e3b2ef380d9abed3f44ba6349dc595f3550)

tokenization_interns1.py

@@ -893,6 +893,10 @@ class InternS1Tokenizer(Qwen2Tokenizer):
         else:
             return self.encoder.get(token, self.encoder.get(self._unk_token))
 
+    def _convert_id_to_token(self, index):
+        """Converts an index (integer) in a token (str) using the vocab."""
+        return self.decoder.get(index, "")
+    
     def convert_tokens_to_string(self, tokens):
         """Converts a sequence of tokens (string) in a single string."""
         text = "".join(tokens)