diff --git a/Project_Model/Libs/BPE/Utils/special_regex_maker.py b/Project_Model/Libs/BPE/Utils/special_regex_maker.py
index 414eabf..fd4ac28 100644
--- a/Project_Model/Libs/BPE/Utils/special_regex_maker.py
+++ b/Project_Model/Libs/BPE/Utils/special_regex_maker.py
@@ -2,6 +2,13 @@ import re
 
 
 def special_regex_maker(special_tokens: list[str]) -> re.Pattern:
+    """ compile a regex for the special token
+    Args:
+        special_tokens (list[str]): the list of special token
+
+    Returns:
+        re.Pattern:
+    """    
 
     REGEX_STR = "|".join(special_tokens)