[Zope] How to check type of variable in DTML

I am passing a variable to a ZSQL method and I need to check whether its a string or a list before it is part of a WHERE statement. How can I check this? <dtml-if mk> CMAKE IN ( <dtml-var "mk[1:-1}"> ) </dtml-if> This works well if its a list but blows up if just a string. Needs to be like this: <dtml-if mk is_A_list> CMAKE IN ( <dtml-var "mk[1:-1}"> ) <dtml-else> <dtml-var sqltest mk column=CMAKE type=nb optional> </dtml-if> Thanks -Allen