def searchUsersByRequest(request, sort_by=None):
    """Search for users matching a set of criteria found in a request.

        This method will look remove any obvious values from the request
        which are not search criteria. It will also remove any fields
        which have an empty string value.
        Duplicate results returned by PAS are filtered so only the first
        result remains in the result set. The results can be sorted on
        sort_by (case insensitive).
        """
