title: Possible error in Python Array operations module
body: <p>While writing a code snippet for a Leetcode question, I noticed that my Python3 arrays were not getting updated as expected.</p>
  
  <p>Basically, I have a 2D array listing players moves for a tic-tac-toe game. Player A plays first, Player B next, Player A next, and so on. My first move is to represent these moves on a 2D array. The array <code>moves</code> listed below mentions the (x,y) co-ordinates of the 3x3 TicTacToe grid that is to be updated.</p>
  
  <pre><code>(0,0)  |  (0,1)  |  (0,2)
  _______|_________|________
   (1,0) |  (1,1)  |  (1,2)
         |         |
  _______|_________|________
  (2,0)  |   (2,1) |  (2,2)
         |         |
  </code></pre>
  
  <pre><code>moves = [[0,0],[2,0],[1,1],[2,1],[2,2]]
  arr=[['']*3]*3
  #print(arr)
  for i in range(len(moves)):
      xC=moves[i][0]
      yC=moves[i][1]
      if(i%2==0):
          #playerA
          arr[xC][yC]='X'
      else:
          #playerB
          arr[xC][yC]='O'  
  print(arr)
  </code></pre>
  
  <p>The variable 'moves' lists the population of only 5 boxes out of 9 boxes in the tic tac toe game, but the output array 'arr' is populated as such:</p>
  
  <pre><code>[['O', 'O', 'X'], ['O', 'O', 'X'], ['O', 'O', 'X']]
  
  </code></pre>
  
  <p>Just fyi: I've been using Py3 for a few years now, and I'm comfortable with it (not a newbie).
  What's your thoughts on the issue?
  A bug in Py3's array module? Let me know. (btw, my first StackOverflow Question!)</p>
  
  <p>The question is at this address: <a href="https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game/" rel="nofollow noreferrer">https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game/</a></p>