That's not even necessary. If you're using <pre>, you can just change one of the angle brackets to its entity name (like &lt;) and PM will obligingly look past the <code></code> tags. But using <pre> means your code/output will not be autowrapped, nor will it be easily downloadable, and you have to manually escape any PM approved HTML tags as well as any of your ampersands that look like entities.

Makeshifts last the longest.