import os
import re
import sys
import logging
import optparse
import MySQLdb
import subprocess

"""Script default configuration
"""
DB_HOST = '127.0.0.1'
DB_PORT = '3306'
DB_USER = 'wlanuser'
DB_PASS = 'wlanpass'
DB_NAME = 'wlandb'

class DB:
"""MySQL wrapper class
"""
def __init__(self, ahost = DB_HOST, aport = DB_PORT, auser = DB_USER, apasswd = DB_PASS, adb = DB_NAME):
   """Initialize database configuration
   """
   self.conn = None
   self.host = ahost
   self.port = aport
   self.user = auser
   self.passwd = apasswd
   self.db = adb

def connect(self):
   """Connect to database
   """
   self.conn = MySQLdb.connect(host=self.host,port=int(self.port),user=self.user,passwd=self.passwd,db=self.db,use_unicode=True, charset="utf8")
   self.conn.autocommit(True);

def cursor(self):
   """Get current cursor of database
   """
   try:
         return self.conn.cursor()
   except (AttributeError, MySQLdb.OperationalError):
         self.connect()
         return self.conn.cursor()

def escape(self, str):
   """Returns escaped string
   """
   if self.conn == None:
         self.connect()
   return self.conn.escape_string(str)

def query(self, sql):
   """Query database with SQL statement
   """
   try:
         cursor = self.conn.cursor()
         cursor.execute(sql)
   except (AttributeError, MySQLdb.OperationalError):
         self.connect()
         cursor = self.conn.cursor()
         cursor.execute(sql)
   return cursor

def close(self):
   """Close connection
   """
   if self.conn != None:
         self.conn.close()

def commit(self):
   """Manual commit database operation
   """
   self.conn.commit()

def parse_command_line(argv):
"""Command line options parser for the script
"""
usage = "usage: %prog [options]"

Problem 1 (Preserving Invariants). For each of the following loop i...