import random

class shuffler(object):
    def __init__(self):
        self.rgen = random.Random()
    def shuffle(self, inpile1, inpile2):
        """Function that shuffles two list of items."""
        if self.rgen.randint(0,1):  #randomly decide which pile is shuffled down first
            (pile1,pile2)=(inpile1,inpile2)
        else:
            (pile1,pile2)=(inpile2,inpile1)
        pile1c = len(pile1)
        pile2c = len(pile2)
        rpile = pile1[0:0] #get blank copy of the passed in object types. Should allow user defined list type objects to work as well
        while pile1c and pile2c:    #while there are still items in both piles execute following logic
            i = self.rgen.randint(1,4)  #to allow for human error get random offset of items to shuffle
            if i > pile1c:  #ensure we don't go out of bounds for the pile
                i = pile1c
            for x in range(0,i):    #append cards to the output pile and remove from shuffle pile
                rpile.append(pile1.pop(0))
                pile1c -= 1
            i = self.rgen.randint(1,4)  #to allow for human error get random offset of items to shuffle
            if i > pile2c:  #ensure we don't go out of bounds for the pile
                i = pile2c
            for x in range(0,i):    #append cards to the output pile and remove from shuffle pile
                rpile.append(pile2.pop(0))
                pile2c -= 1
        #check for which pile has left over items if any do
        if pile1c:
            rpile.extend(pile1)
        elif pile2c:
            rpile.extend(pile2)
        return rpile
    def shuffledeck(self, deck):
        """Function that shuffles a list type object"""
        i = len(deck) #get length of the deck object to shuffle
        cut = (i // 2) + self.rgen.choice(range(-4,5)) #find half way point of deck +/- human error factor
        pile1 = deck[0:cut]
        pile2 = deck[cut:]
        return self.shuffle(pile1,pile2)

if __name__ == '__main__':
    myshuffle = shuffler()
    deck = range(1,53)
    print deck
    for i in range(1,5):
        deck = myshuffle.shuffledeck(deck)
    print deck