title: Formatting a filename in python
body: <p>I would like to format a string based on the input. For example if the line count is 1, the output must be <code>image00001.png</code> and if the line count is 400, the output is <code>image00400.png</code></p>
  <p>I use the following to do so</p>
  <pre><code>filename = &quot;image%05d.png&quot;.format(line_count)
  </code></pre>
  <p>but it doesn't work as expected. What am I missing?</p>