code: func GxKML(children ...Element) *CompoundElement {
  	kml := KML(children...)
  	// FIXME find a more correct way to do this
  	kml.Attr = append(kml.Attr, xml.Attr{Name: xml.Name{Local: "xmlns:gx"}, Value: GxNamespace})
  	return kml
  }
docs: // GxKML returns a new kml element with Google Earth extensions.