diff --git a/src/callbacks.py b/src/callbacks.py
index cc16ad22a..915b44d0a 100644
--- a/src/callbacks.py
+++ b/src/callbacks.py
@@ -231,6 +231,7 @@ class Tokenizer:
         return ret
 
     def tokenize(self, s):
+        """Tokenizes a string according to supybot's nested argument format."""
         lexer = shlex.shlex(StringIO(s))
         lexer.commenters = ''
         lexer.quotes = '"'