diff --git a/android-interact.sh b/android-interact.sh
index aa29a1d..28065d7 100755
--- a/android-interact.sh
+++ b/android-interact.sh
@@ -1,6 +1,6 @@
 #!/bin/bash -e
 # File: android-interact.sh
-# Date: Sun Feb 01 17:26:48 2015 +0800
+# Date: Sun Apr 12 21:19:07 2015 +0900
 # Author: Yuxin Wu <ppwwyyxxc@gmail.com>
 
 source compatibility.sh
diff --git a/report.sh b/count-message.sh
similarity index 88%
rename from report.sh
rename to count-message.sh
index 40e3566..7d496cb 100755
--- a/report.sh
+++ b/count-message.sh
@@ -1,16 +1,16 @@
 #!/bin/bash -e
-# File: android-interact.sh
-# Date: Sat Mar  7 20:57:51 2015 +0800
+# File: count-message.sh
+# Date: Sun Apr 12 21:01:01 2015 +0900
 # Author: Kangjing Huang <huangkangjing@gmail.com>
 
 
 if [[ -z $1 ]]
-then 
+then
     echo "Usage: $0 [Directory of text messages]"
     exit 1
 fi
 
-echo -e "Filename\tCounts of message\tCounts of chars\tCounts of words" 
+echo -e "Filename\tCounts of message\tCounts of chars\tCounts of words"
 
 SAVEIFS=$IFS
 IFS=$(echo -en "\n\b")
diff --git a/libchat/libchat.py b/libchat/libchat.py
index 0662163..360dc6a 100644
--- a/libchat/libchat.py
+++ b/libchat/libchat.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python2
 # -*- coding: UTF-8 -*-
 # File: libchat.py
-# Date: Sat Mar 28 00:08:29 2015 +0800
+# Date: Sun Apr 12 21:08:51 2015 +0900
 # Author: Yuxin Wu <ppwwyyxxc@gmail.com>
 import sqlite3
 import os
@@ -14,6 +14,16 @@ NUM_FIELDS = 8
 ChatMsgBase = namedtuple('ChatMsgBase',
           ['source', 'time', 'sender', 'chatroom',
            'text', 'image', 'sound', 'extra_data'])
+""" source: unicode,
+    time: datetime,
+    sender: unicode,
+    chatroom: unicode,
+    text: unicode,
+    image: string,
+    sound: string,
+    extra_data: string
+"""
+
 class ChatMsg(ChatMsgBase):
     def __repr__(self): # repr must return str?
         return "Msg@{}/{}-{}/{}/{}/{}/{}".format(
@@ -56,6 +66,7 @@ class SqliteLibChat(object):
               ','.join(['?']*NUM_FIELDS)), tp)
 
     def add_msgs(self, msgs):
+        """ each message is a ChatMsg instance"""
         self.c = self.conn.cursor()
         for m in msgs:
             self._add_msg(SqliteLibChat.prefilter(m))