func isMagic(_: Int) -> Bool? {
    return false
}

func foo1(s: AnySequence<Int>) {
    _ = s.flatMap(isMagic) //  error: cannot convert value of type '(Int) -> Bool?' to expected argument type '((Int)) -> _'
    _ = s.flatMap { _ -> Bool? in // error: declared closure result 'Bool?' is incompatible with contextual type 'String'
        return false
    }
}

func foo2(s: AnySequence<Int>) {
    let a = Array(s) // ??? oops, type is Array<(Int)>
    _ = a.flatMap(isMagic) // error: cannot convert value of type '(Int) -> Bool?' to expected argument type '((Int)) -> String?'
    _ = a.flatMap { _ -> Bool? in // error: declared closure result 'Bool?' is incompatible with contextual type 'String'
        return false
    }
}

func foo3(s: AnySequence<Int>) {
    let a: Array<Int> = Array(s)
    _ = a.flatMap(isMagic) // works
    _ = a.flatMap { _ -> Bool? in // works
        return false
    }
}

func foo4(s: AnySequence<Int>) {
    let a = s.map { $0 }
    _ = a.flatMap(isMagic) // works
    _ = a.flatMap { _ -> Bool? in // works
        return false
    }
}