Watir: how to get the url in a frame

I’m using this code:

class GiveMe(frame)
def initialize
@frameURL=frame.url()

a few operations with this data

return result
end
end

nav=Watir::IE.new()
nav.goto(“http://es-aas.com/customers/info/ettem.do”)

isok=GiveMe.new(nav.frame(“top”).frame(“data”))

isok=GiveMe.new(nav.frame(“main”))

isok=GiveMe.new(nav)

This is working only for the last case
How can I get the url of a frame?

Thanks in advance.

No ideas?