Cannot return value referencing local variable in closure

Hello! I am writing my pet app and spent a lot of time trying to figure out why this error occurs. I am building a future stream of ip's, which should ping each ip in parrallel, so I guess i must use buffer_unordered on a stream of futures. But compiler complains about variable fetcher4 which is an Arc. I would appreciate any help for this problem. Code snippet: some_future_stream_of_strings .map(move |sub| { let fetche...