[Zope] testing query results for presence in an array

[David Siedband]

This is for a page where the user can update the listing for a 
particular project.  I have a query that returns a complete list of all 
locations, and another query that returns the list of locations already 
selected for a given project.  What I'd like to do is render the 
complete list in a multiple selection form element and have the 
keywords that are already entered for the project appear as selected in 
this list.  Here's the code:

  <dtml-in "queries.getPlacesForHypothesis()" prefix=obj>
<select multiple name="places">
   <dtml-in "queries.getPlacesAll()">
     <option value="<dtml-var PlaceID>" <dtml-if "PlaceID in obj_items" 
 > selected </dtml-if>><dtml-var PlaceName></option>
   </dtml-in>
</select>
</dtml-in>


About the Z SQL queries:
getPlacesAll() returns an array of PlaceID's and PlaceName's
getPlacesForHypothesis() returns a sequence of PlaceID's

How do I test to see if a place is in in the list of selected places 
for a project?

thanks,

David