calculates days of each month with a simple formula thought up by Curtis McEnroe

days_in_month.py

#!/usr/bin/env python
# http://cmcenroe.me/2014/12/05/days-in-month-formula.html

from __future__ import print_function
from argparse import ArgumentParser
import math

parser = ArgumentParser()

parser.add_argument(
    'month',
    metavar='MONTH',
    type=int,
    choices=range(1,13),
    help='Number of month that you want the number of days from'
)

args = parser.parse_args()

def days(month):
    days = 28
    days = days + (month + math.floor(month/8)) % 2 + 2 % month + 2 * math.floor(1/month)
    return int(days)

print(days(args.month))