title: Traversing through Matrix in Python
body: <p>I'm new to Python and I'm trying to create a simple tictactoe game to learn the syntax and keep getting an error <code>TypeError: object of type 'int' has no len()</code> when running the following:</p>
  
  <pre><code>board = [ 
              ['|', '|', '|' ],
              ['|', '|', '|'],
              ['|', '|', '|'] 
          ] 
  
  def tictactoe ():
  
      print('\n'.join([''.join(['{:4}'.format(item) for item in row]) for row in board]))
  
      print(len(board))
  
      for i in range(0,len(board)):
          for j in range(0,len(i)):
              print(i,j)
  </code></pre>