Array+Equatable.swift

extension Array where Element: Equatable {

    func exists(_ item: Element) -> Bool {
        if let _ = self.indexOf(item) {
            return true
        }
        return false
    }

    func indexOf(_ item: Element) -> Int? {
        return self.enumerated().filter({ $0.element == item }).map({ $0.offset }).first
    }

    mutating func remove(item: Element) -> Element? {
        if let index = indexOf(item) {
            return self.remove(at: index)
        }
        return nil
    }

    func removed(_ item: Element) -> [Element] {
        return self.filter({ $0 != item })
    }
}