Smarty if / else使用Post参数？

I'm using the Smarty template system and can't seem to find any documentation on how to do this...

I want to check what parameters are sent through Post. If the parameters last7, last30, last60, or full DO NOT exist, I want to display "This is not working!". If any of those parameters have been posted, I want "This is working" to be displayed.

Does anyone know how to do this in the Smarty template system?

The Smarty docs don't have any info that I can find on using if/else with parameters...

Been a long time since I used Smarty (why not just use PHP), but this seems right:

{if isset($smarty.post.last7, $smarty.post.last30, $smarty.post.last60)}
    This is working
{else}
    This is not working!
{/if}