如何将xml声明和处理指令添加到XQuery结果中？

xml { declaration } { processing-instruction }

xml version "1.0" encoding "UTF-8"

xml-stylesheet type "text/xsl" href "style.xsl"

let $result := <book>
                  <title>XQuery 101</title>
                  <author>John Doe</author>
              </book>
return
    xml {
        xml version "1.0" encoding "UTF-8",
        xml-stylesheet type "text/xsl" href "style.xsl"
    } {
        $result
    }