Groovy create XML

How can I create XML in Groovy?

def xml = new groovy.xml.MarkupBuilder()
xml.langs(type:"current"){
  language("Java")
  language("Groovy")
  language("JavaScript")
}

Yeah, I know, it works.. But i need XML like this:

<root>
  <one param="var">
    <some param="var">variable</some>
    <some param="var">variable</some>
    ...
  </one>
  <two>
    <some param="var">variable</some>
    <some param="var">variable</some>
    <some param="var">variable</some>
    ...
  </two>
  ...
</root>

I will have loop in loop. Inner for and outer for , ... but how can I add it to XML?

Thanks!