Customizing structs to use Diffable

TicketShort+Diffable.swift

extension TicketShort: Diffable {
    
    var diffIdentifier: String {
        return id
    }
    
    static func ==(lhs: TicketShort, rhs: TicketShort) -> Bool {
        return lhs.id == rhs.id
    }

    func diffable() -> ListDiffable {
        return DiffableBox(value: self, identifier: self.diffIdentifier as NSObjectProtocol, equal: ==)
    }

}