ChristmasSong.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"]

for index, verse in enumerate(verses):
    day = index + 1
    previous_verses = verses[:day]  # This cuts out and returns all elements from 0, to day from the list of verses
    ordered_verses = reversed(previous_verses)
    # Shockingly, this ^ reverses the list, so we have a list of elements starting from the newest item to the oldest
    chorus = "On the {} day of Christmas my true love sent to me,".format(day)
    # Format, based on C's format, is a very flexible tool, in this case it replaces {} with day
    print(chorus, ', '.join(ordered_verses))