title: python type error: does not support indexing
body: <pre><code>        import simplegui
          import random        
          top=52
          in_play=False
          suits=('C','S','H','D')
          ranks=('A','2','3','4','5','6','7','8','9','T','J','Q','K')
          alist=range(0,52)
  
          def deal():
              global outcome,in_play,alist,top
              if not in_play:
                  alist=range(0,52)
              in_play=True
              r = random.randint(0,top)
              card=Card(suits[alist[r]//13],ranks[alist[r]//4])  #line 73
              alist=alist.remove(alist[r])
              top=top-1
              return card
      class Card:
          def __init__(self,suit,rank):
              global suits,ranks
              if (suit in suits) and (rank in ranks):
                  self.suit=suit
                  self.rank=rank
              else:
                  self.suite=None
                  self.rank=None
                  print "invalid card:",suit,rank
  
          def  __str__(self):
              return self.suit+self.rank
          def get_suit(self):
              return self.suit
          def get_rank(self):
              return self.rank
          def draw(self,canvas,pos):
              card_loc=(card_centre[0]+card_size[0]*ranks.index(self.rank),
                        card_centre[1]+card_size[1]*suits.index(self.suit) )
              canvas.draw_image(card_images,card_loc,card_size,[pos[0]+card_centre[0],pos[1]+card_centre[1]],card_size)
  </code></pre>
  
  <p>this a part of the code i ran in codeskulptor
  its showing an error:
  Line 73: TypeError: 'NoneType' does not support indexing
  ................................................................................................................................................................</p>