Add gmask token id

tokenization_chatglm.py

@@ -200,6 +200,12 @@ class ChatGLMTokenizer(PreTrainedTokenizer):
 
         """ Initialisation """
 
+    @property
+    def gmask_token_id(self) -> Optional[int]:
+        if self.gmask_token is None:
+            return None
+        return self.convert_tokens_to_ids(self.gmask_token)
+
     @property
     def eop_token_id(self) -> Optional[int]:
         """