title: Using sort! function in DrRacket
body: <p>I'm dealing with vectors and trying to use <code>sort!</code> function which is listed <a href="http://sicp.ai.mit.edu/Fall-2003/manuals/scheme-7.5.5/doc/scheme_toc.html#TOC87" rel="nofollow noreferrer">here</a>. However I get unbound identifier error. At the top of editor, I specified the language as</p>
  <pre><code> #lang scheme
  </code></pre>
  <p>Should I load another module to use this function?</p>