loromits

struct DoublyLinkedList<Element> {
    class Node {
        var value: Element
        weak var next: Node?
        var previous: Node?
        
        init(_ value: Element, next: Node?, previous: Node?) {
            (self.value, self.next, self.previous) = (value, next, previous)
            next?.previous = self
            previous?.next = self

loromits

struct Stack<Element> {
    fileprivate class Node {
        let value: Element
        var previousNode: Node?
        
        init(_ value: Element, previousNode: Node?) {
            self.value = value
            self.previousNode = previousNode
        }
    }