[Zope] <!--#in string or list--> problem

[Philip Aylesworth]

I am having a problem with a form that has check boxes on it. If several
checkboxes are checked it works great. If only one is checked then it
gives the following error:

  Traceback (innermost last):
File lib/python/OFS/DTMLMethod.py, line 151, in __call__
  (Object: editmanystatus.dtml)
File lib/python/DocumentTemplate/DT_String.py, line 513, in __call__
  (Object: editmanystatus.dtml)
File lib/python/DocumentTemplate/DT_In.py, line 628, in renderwob
  (Object: nums)
InError: Strings are not allowed as input to the in tag.

I can see that it is because instead of a list it now has a single
string but I don't know how to handle this. Is there a way to force an
object to be a list whether it is a list or a single string? Or, do I
have to test for this as a special case?

Right now I have:

<!--#in nums-->
  <!--#call "REQUEST.set('num',_['sequence-item'])"-->
  <!--#call editstatus-->
<!--#/in-->

where nums is a check box input from my form.

Phil A