title: Python 3 format method - tuple index out of range
body: <p>I have a problem with the format method in Python 3.4.2. Shows me the following error: </p>
  
  <pre><code>Traceback (most recent call last):
    Python Shell, prompt 2, line 3
  builtins.IndexError: tuple index out of range
  </code></pre>
  
  <p>The code:</p>
  
  <pre><code>A = "{0}={1}"
  B = ("str", "string")
  C = A.format(B)
  print (C)
  </code></pre>
  
  <p>The tuple contains two strings with indexes 0 and 1 and this error should not be displayed.  </p>