[Zope] What If It Doesn't Have a Key?

Hi; I have this line of code: <span tal:condition="python:request.has_key('checkbox_1')" tal:omit-tag=""> I would like to do the exact opposite of that. In other words, have the condition render if checkbox_1 does not exist. How do I do that? TIA, Tony ________________________________________________________________________ AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com.