[xquery-talk] Wrap element constructor and output disappears

[Ihe Onwuka]

Also posted on SO
https://stackoverflow.com/questions/61986249/cannot-wrap-element-around-xquery-output
but
happy to get an answer anywher.

Returning to XQuery after a long hiatus.

let $root := <a:b xmlns:a="ans" xmlns:c="cns"/>
     for $prefix in in-scope-prefixes($root)[not(. = ('xml', 'xsi'))]
      return
          namespace-uri-for-prefix($prefix,$root) !
              <param name="{$prefix}" value="{.}"/>

gives the expected

<param name="a" value="ans"/>
<param name="c" value="cns"/>

But if I try to wrap an element around that output like below nothing is
returned

<parameters>{
let $root := <a:b xmlns:a="ans" xmlns:c="cns"/>
     for $prefix in in-scope-prefixes($root)[not(. = ('xml', 'xsi'))]
      return
          namespace-uri-for-prefix($prefix,$root) !
              <param name="{$prefix}" value="{.}"/>
}</parameters>

So what is wrong and how do I wrap the output in a parameters element?
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