title: str.format() raises KeyError
body: <p>The following code raises a <code>KeyError</code> exception:</p>
  
  <pre><code>addr_list_formatted = []
  addr_list_idx = 0
  
  for addr in addr_list: # addr_list is a list
      addr_list_idx = addr_list_idx + 1
      addr_list_formatted.append("""
          "{0}"
          {
          "gamedir"  "str"
          "address"  "{1}"
          }
      """.format(addr_list_idx, addr))
  </code></pre>
  
  <p>Why?</p>
  
  <p>I am using Python 3.1.</p>