title: Accounting for lower and uppercase in glob
body: <p>I need to pass an extension to function, and then have that function pull all files with that extension in both lower and uppercase form.</p>
  
  <p>For example, if I passed <code>mov</code>, I need to function to do:</p>
  
  <pre><code>videos = [file for file in glob.glob(os.path.join(dir, '*.[mM][oO][vV]'))] 
  </code></pre>
  
  <p>How would I accomplish the lower + upper combination above given a lowercase input?</p>