Extract EntityDescriptor from Shibboleth bulk metadata file and remove Extensions nodes

ShibbolethMetadata2OpenAM.xqy

xquery version "1.0-ml";
declare namespace html = "http://www.w3.org/1999/xhtml";
declare namespace a = "urn:oasis:names:tc:SAML:2.0:metadata";

<EntityDescriptor xmlns="urn:oasis:names:tc:SAML:2.0:metadata" 
  xmlns:ds="http://www.w3.org/2000/09/xmldsig#" 
  xmlns:mdrpi="urn:oasis:names:tc:SAML:metadata:rpi" 
  xmlns:mdui="urn:oasis:names:tc:SAML:metadata:ui" 
  xmlns:shibmd="urn:mace:shibboleth:metadata:1.0" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
  Name="urn:mace:switch.ch:SWITCHaai" 
  validUntil="2012-09-09T19:59:01Z" 
  xsi:schemaLocation="urn:oasis:names:tc:SAML:2.0:metadata saml-schema-metadata-2.0.xsd urn:mace:shibboleth:metadata:1.0 shibboleth-metadata-1.0.xsd urn:oasis:names:tc:SAML:metadata:ui saml-metadata-ui-1.0.xsd http://www.w3.org/2000/09/xmldsig# xmldsig-core-schema.xsd">
{
let $id := "https://aai-login.fh-htwchur.ch/idp/shibboleth"
for $entity in doc()/a:EntitiesDescriptor/a:EntityDescriptor[@entityID = $id]
let $entityId := $entity/@entityID
let $idpssoDescriptor := $entity/IDPSSODescriptor/(@*, * except Extensions)
let $attributeAuthorityDescriptor := $entity/AttributeAuthorityDescriptor/(@*, * except Extensions)
return ($entityId, <IDPSSODescriptor>{$idpssoDescriptor}</IDPSSODescriptor>, <AttributeAuthorityDescriptor>{$attributeAuthorityDescriptor}</AttributeAuthorityDescriptor>) 
}</EntityDescriptor>

$id should be an input parameter, like the classical bash $1