Christmas.py

verses = ["a Partridge in a Pear Tree", "Two Turtle Doves", "Three French Hens", "Four Calling Birds",
          "Five Gold Rings", "Six Geese-a-Laying", "Seven Swans-a-Swimming", "Eight Maids-a-Milking",
          "Nine Ladies Dancing", "Ten Lords-a-Leaping", "Eleven Pipers Piping", "Twelve Drummers Drumming"]
days = {index - 1: ', '.join(reversed(verses[:index - 1])) for index, verse in enumerate(verses)}

def get_day(day): 
    return "On the {} day of Christmas my true love sent to me,".format(day) + days[day]

def get_presents(start, end=None): 
    return sum(range(start, end + 1)) if end else sum(range(start))

print(get_presents(11, 12))