[Zope] conditionals inside dtml-let expressions

Is there a straightforward way to bind one of two values to a let variable depending on the value of another variable? In C/C++/Java I would use the ?: operator, but Python doesn't have that. Or should I just bind the variable to None then set it later with something like <dtml-let var=None> <dtml-if "testvar==targetval"> <dtml-var expr="_.set(var, 'yes')> <dtml-else> <dtml-var expr="_.set(var, 'no')> </dtml-if> </dtml-let>