title: Key Error (0, 0) when trying to use tuple as a dictionary key in Python
body: <p>I am getting the <code>Key Error: (0, 0)</code>. In this part of my code, I am trying to create to dictionary of of block in my grid that has the key (x, y).
  Here's my code:</p>
  
  <pre><code>self.block_list = {}
  for x in range(0, self.width):
      for y in range(0, self.height):
          self.block_list[(x, y)] 
  </code></pre>
  
  <p>I don't understand why (0, 0) is not being included in the dictionary.</p>