XML attribute mapping rule with complex XPath

xpath-rule.xml

<?xml version="1.0" encoding="UTF-8"?>
<mapping xmlns="http://docs.rackspace.com/identity/api/ext/MappingRules"
         xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion"
         xmlns:xs="http://www.w3.org/2001/XMLSchema"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         version="RAX-1">
   <rules>
      <rule>
        <remote>
            <attribute multiValue="true"
                       path="
       (:
          If the number of seconds is even, then the role should be
          nova:admin and lbaas:admin

          Otherwise the roles should be nova:observe and lbaas:observer.
       :)
       if ((xs:integer(seconds-from-time(current-time())) mod 2) = 0)
             then ('nova:admin','lbaas:admin')
             else ('nova:observer','lbaas:observer')
                       "/>
        </remote>
        <local>
            <user>
               <name value="{D}"/>
               <email value="{D}"/>
               <expire value="{D}"/>
               <domain value="78334"/>
               <roles value="{0}"/>
            </user>
         </local>
      </rule>
   </rules>
</mapping>