Update api_server: clean

api_server.py

@@ -1,9 +1,8 @@
 #! /usr/bin/env python
 # -*- coding: utf-8 -*-
 # vim:fenc=utf-8
-import logging
-from calendar import prmonth
 
+import logging
 import werkzeug.exceptions
 from flask import Flask, request, jsonify
 from datetime import datetime, timedelta