diff --git a/src/m.wxsy.net/logger.py b/src/m.wxsy.net/logger.py
index b9f9a06..36cfaf8 100644
--- a/src/m.wxsy.net/logger.py
+++ b/src/m.wxsy.net/logger.py
@@ -1,6 +1,12 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
+"""
+Logger module:
+  INFO level -> stderr
+  DEBUG level -> runtime.log
+"""
+
 import sys
 import logging
 import colorlog