collections

type Collection[T any] interface {
	HasElements() bool
	IsEmpty() bool
}

type DoublyLinkedNode[T interface{}] struct {
	Value      T
	Prev, Next *DoublyLinkedNode[T]
}

type Set[T comparable] interface {
	fmt.Stringer
	Size() int
	Contains(T) bool
	Add(T) bool
	Remove(T) bool
	AddAll(...T) bool
	Values() []T
}

type Stack[T any] interface {
	Collection[T]
	Push(value T)
	Pop() T
}