[Zope] - Problem with multiple inputs

[skip@calendar.com (Skip Montanaro)]

One of my search forms allows people to search using one or more keywords.
If they select one keyword it's delivered as a string.  If they select
multiple keywords it's delivered as a list.  In the search results page I
want to generate a new search form that contains the input parameters from
the search to make it easy to generate a related search.  I currently have

  <!--#if keywords-->
    <!--#in keywords-->
      <input type=hidden name="keywords" value="<!--#var sequence-item-->">
    <!--#/in-->
  <!--#/if-->

This fails if the user selected just a single keyword, since the keywords
parameter is a string.  Is there some clean way to work around this problem?
The only thing I can see is something like

  <!--#if keywords-->
    <!--#if "type(REQUEST['keywords']) == type('')"-->
      <input type=hidden name="keywords" value="<!--#var keywords-->">
    <!--#else-->
      <!--#in keywords-->
	<input type=hidden name="keywords" value="<!--#var sequence-item-->">
      <!--#/in-->
    <!--#/if-->
  <!--#/if-->

which fails because the builtin function type is apparently not available.
I also tried using "_.type(...)" but that failed with an AttributeError (was
that the correct syntax?).  My short-term solution is to add a hidden
parameter with a dummy value that guarantees if the user selects a keyword
there will be at least two keywords, thus I'll get a list I can loop over
with #in. Is there a cleaner way out of this mess?

Thanks,

Skip Montanaro	| Mojam: "Uniting the World of Music" http://www.mojam.com/
skip@mojam.com  | Musi-Cal: http://www.musi-cal.com/
518-372-5583