title: KeyError with integer tuples as keys
body: <p>Following is the code </p>
  
  <pre><code>values = { (0,0) : "_", (0,1) : "_", (0,2) : "_",
             (1,0) : "_", (1,1) : "_", (1,2) : "_",
             (2,0) : "_", (2,1) : "_", (2,2) : "_" }
  
  
  def draw_matrix():
      matrix = "\t ___ ___ ___\n\t|_{(0,0)}_|_{(0,1)}_|_{(0,2)}_|\n\t|_{(1,0)}_|_{(1,1)}_|_{(1,2)}_|\n\t|_{(2,0)}_|_{(2,1)}_|_{(2,2)}_|"
      print(matrix.format(**values))
      print("\nUse numpad keys to enter your mark")
  
  draw_matrix()
  </code></pre>
  
  <p>When I access values of keys individually, it works fine. But, I can't unpack this dictionary using .format() for some reason.</p>
  
  <pre><code>KeyError: '(0,0)'
  </code></pre>
  
  <p>It's the same if I use numbers. This is gonna be a tic-tac-toe game so I used the numpad keys previously. I cannot use the tuples as strings because I'll need to use them to check for winning conditions. That works perfectly, though.</p>