'When Mario becomees big, converts all fireflower powerups to
mushroom powerups'

def convert_mushrooms_to_fireflowers(self):

    for brick in self.brick_group:
        if (brick.contents == c.MUSHROOM):
            brick.contents = c.FIREFLOWER
    for coin_box in self.coin_box_group:
        if (coin_box.contents == c.MUSHROOM):
            coin_box.contents = c.FIREFLOWER
