Determine the build week date of Cisco Equipment

ciscobuilddate.py

from datetime import date, timedelta
import calendar

def builddate(serial):
    '''
    Returns a date object of the manufactured date.
    '''
    # The serial format is LLLYYWWSSSS where YY and WW denote the build week.
    # YY -- Decimal number where 00 denotes 1996 as the starting year.
    # WW -- Decimal number of the week of the year it was built.
    year = 1996 + int(serial[3:5])
    week = timedelta(days=7 * int(serial[5:7]))
    mdate = date(year, 1, 1) + week
    return mdate

if __name__ == '__main__':
    serial = raw_input('Enter Cisco Serial Number : ')
    mdate = builddate(serial)
    cal = calendar.month(mdate.year, mdate.month).split('\n')[2:-1]
    weekno = 0
    for week in cal:
        if str(mdate.day) in week:
            weekno = cal.index(week)
    prettymap = {1: 'st', 2: 'nd', 3: 'rd', 4: 'th', 5: 'th'}
    print '\n%d%s week in %s\n' % (weekno, prettymap[weekno], mdate.strftime('%B, %Y'))