[Tutor] WAIDW - copying list within a recursive function

[Ole Jensen]

WAIDW == (W)hat (A)m (I) (D)oing (W)rong

(Question put short:
Why does this function return; None?
###
def shuffle(i=24, deck=[]):
    a = [ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, jack, queen, king]
    deck.append(a[:])
    print deck
    if i > 0:
        print "if i > 0"
        shuffle(i-1, deck)
    elif i == 0:
        print "elif i == 0"
        print deck
        return deck
    else: print "failsafe"
###

Read below for more detailed describtion of my wrong doings ;)
)

I'm trying to create a list representing a stack of cards containing six card decks, I do not really care much of the about colour so my stack would come to look like this:

###
stack = [[ace, 2, 3,....., king], [ace, 2, 3,....., king],........,[ace, 2, 3,...., king]
###

The above should symbolise a list (stack) with 24 lists of different colours (allthough the colours e.g. clubs or hearts, are not shown as such).

Now call me lazy but I would prefer not to type all those those identical lists manually (both easthatically and labour wise), so I saw this as a good time to try to play around  with recursive functions (easily done in a forloop with two lines, but now I'm stubborn). 
The best bit of code I have come up with untill now is this:

###
def shuffle(i=24, deck=[]):
    a = [ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, jack, queen, king]
    deck.append(a[:])
    print deck
    if i > 0:
        print "if i > 0"
        shuffle(i-1, deck)
    elif i == 0:
        print "elif i == 0"
        print deck
        return deck
    else: print "failsafe"
###
(The print statements are for testing)

Which of course doesn't work (Otherwise I wouldn't be writing this mail)!
The the output ends up like this:
[[11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10]]
if i > 0
[[11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10], [11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10]]
if i > 0
etc. etc.
These few lines above shows me that everything shaping about nicely, the list is looking the way it's supposed to.

In the end of the output i finally equals 0, and the list is printed a final time looking complete (len(deck) == 24). When the next command in the sourcecode reads: return deck.

###
elif i == 0:
    print "elif i == 0"
    print deck
    return deck
###

My question is this:
If the list "deck" is as it is supposed to (and it looks to be), then why does the function return; None?

In advance thanks for any enlightment.

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