FQL: Fetch friends of a friend

How could I fetch the friends of a friend of mine with FQL or something other of the FB-APIs? At the normal website of开发者_开发知识库 Facebook it's possible to see the friends of a friend of mine if I visit his profile and add ?sk=friends to the url.

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According to the FQL docs on the friends table

the friends of friends cannot be retrieved.

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When you try to access a friend's friends you'll get this message:

"Can only lookup for the logged in user 
or the logged in user's friends 
that are users of your app."

So you can only retrieve a friend's friends who have authorized your app.

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Friends of friend can access only when one friend of your friend, your friend and you (loged user) use same app and give permission to access there data.