title: Populate parameter list from XML
body: <p>I need to pull a list of IDs into a powershell paramater validateset like so: </p>
  
  <pre><code>function Do-Stuff {
     [Cmdletbinding()] 
     param(
          [ValidateSet("Seattle","NewYork","London","Atlanta" )]
          [String]$Site
      )
  </code></pre>
  
  <p>Instead of manually specifying the cities in the set, I'd like to pull from an existing xml document that already lists them all. Once loaded, the site names appear in $xml.var.sites.id. Is this possible, and probably more importantly, is it a good idea? </p>