iterator

type DeleteIterator[T any] interface {
	Iterator[T]

	// Delete deletes the current iterator element;
	// that is, the one returned by the last call to Next.
	// Delete should panic if called before Next or after
	// Next returns false.
	Delete()
}

type Iterator[T any] interface {
	// Next checks if there is a next value in the iteration or not
	HasNext() bool
	// Next returns the next value in the iteration if there is one,
	// and reports whether the returned value is valid.
	// Once Next returns ok==false, the iteration is over,
	// and all subsequent calls will return ok==false.
	Next() (item T, ok bool)
}

type PrevIterator[T any] interface {
	Iterator[T]

	// Prev moves the iterator to the previous position.
	// After calling Prev, Next will return the value at
	// that position in the container. For example, after
	//   it.Next() returning (v, true)
	//   it.Prev()
	// another call to it.Next will again return (v, true).
	// Calling Prev before calling Next may panic.
	// Calling Prev after Next returns false will move
	// to the last element, or, if there are no elements,
	// to the iterator's initial state.
	Prev()
}

type SetIterator[T any] interface {
	Iterator[T]

	// Set replaces the current iterator element with v.
	// Set should panic if called before Next or after
	// Next returns false.
	Set(v T)
}

type StopIterator[T any] interface {
	Iterator[T]

	// Stop indicates that the iterator will no longer be used.
	// After a call to Stop, future calls to Next may panic.
	// Stop may be called multiple times;
	// all calls after the first will have no effect.
	Stop()
}