title: Trouble using python re with the format option
body: <p>I have multiple files of the format <strong>myfilexyz-200407171758.tar.gz</strong></p>
  <p>(<strong>myfilexyz</strong>)-(<strong>200407171758</strong>).tar.gz</p>
  <p>Group1 is a variable. <br/>
  Group2 can be of 12 to 14 digits.</p>
  <p>Using variable substitution, I can get this working</p>
  <p><code>r = re.compile('(%s)-(\d){12,13}.tar.gz' %myvar)</code></p>
  <br/>
  <br/>
  <p>But if I were to try the newer format  method, I get into trouble</p>
  <p><code>r = re.compile('({})-(\d){12,14}.tar.gz'.format(myvar))</code></p>
  <p><em>key '12,14' has no corresponding arguments</em></p>
  <p>Obviously the {12,14} is messing up format. Is there a way around this problem and still use the format method for substitution?</p>