let $results :=
  sem:sparql(
  "
    PREFIX  skosxl: <http://www.w3.org/2008/05/skos-xl#>
        PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
        PREFIX  owl:  <http://www.w3.org/2002/07/owl#>
        PREFIX  skos: <http://www.w3.org/2004/02/skos/core#>
        PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>
        PREFIX slc: <http://www.smartlogic.com/2014/08/semaphore-core#>

  select  ?relation ?value
  where
  {
  $input ?relation ?c .
  OPTIONAL {
    ?c skosxl:prefLabel/skosxl:literalForm|skosxl:literalForm ?d .
  }
      BIND ( if (bound(?d), ?d, ?c) as ?value )
  }
  ", $bindings
  )

let $doc :=  <test>{
  for $item in $results
    return element {map:get($item, 'relation')} {map:get($item, 'value')}
    }</test>

 return $doc