type Element[T any] struct {

	// The value stored with this element.
	Value T
	// contains filtered or unexported fields
}

type List[T any] interface {
	// PushBack inserts a new element e with value v at the back of list l and returns e.
	PushBack(v T) *Element[T]

	// PushBackList inserts a copy of another list at the back of list l.
	// The lists l and other may be the same. They must not be nil.
	PushBackList(other List[T])

	// PushFront inserts a new element e with value v at the front of list l and returns e.
	PushFront(v T) *Element[T]

	// PushFrontList inserts a copy of another list at the front of list l.
	// The lists l and other may be the same. They must not be nil.
	PushFrontList(other List[T])

	// MoveToFront moves element e to the front of list l.
	// If e is not an element of l, the list is not modified.
	// The element must not be nil.
	MoveToFront(e *Element[T])

	// MoveToBack moves element e to the back of list l.
	// If e is not an element of l, the list is not modified.
	// The element must not be nil.
	MoveToBack(e *Element[T])

	// MoveAfter moves element e to its new position after mark.
	// If e or mark is not an element of l, or e == mark, the list is not modified.
	// The element and mark must not be nil.
	MoveAfter(e, mark *Element[T])

	// MoveBefore moves element e to its new position before mark.
	// If e or mark is not an element of l, or e == mark, the list is not modified.
	// The element and mark must not be nil.
	MoveBefore(e, mark *Element[T])

	// Remove removes e from l if e is an element of list l.
	// It returns the element value e.Value.
	// The element must not be nil.
	Remove(e *Element[T]) T

	// InsertBefore inserts a new element e with value v immediately before mark and returns e.
	// If mark is not an element of l, the list is not modified.
	// The mark must not be nil.
	InsertBefore(v T, mark *Element[T]) *Element[T]

	// InsertAfter inserts a new element e with value v immediately after mark and returns e.
	// If mark is not an element of l, the list is not modified.
	// The mark must not be nil.
	InsertAfter(v T, mark *Element[T]) *Element[T]

	// Front returns the first element of list l or nil if the list is empty.
	Front() *Element[T]

	// Back returns the last element of list l or nil if the list is empty.
	Back() *Element[T]

	// Len returns the number of elements of list l.
	// The complexity is O(1).
	Len() int

	// Clear clears the list l.
	Clear()
}