title: Key error '0' with dict format
body: <p>I'm still a beginner in Python, and I wanted to know why this :</p>
  
  <pre><code>    dict = {}
      dict[0] = '123'
      a = 0
      if dict["{}".format(a)]["{}".format(a)] == '1':
          print('True')
  </code></pre>
  
  <p>gives me a Key Error '0' but not this :</p>
  
  <pre><code>    dict = {}
      dict[0] = '123'
      if dict[0][0] == '1':
         print('True')
  </code></pre>
  
  <p>Thanks in advance.</p>