e.prev = at
	e.next = at.next
	e.prev.next = e
	e.next.prev = e
	e.list = l
	l.len++
	return e
}

// insertValue is a convenience wrapper for insert(&_Element[T]{Value: v}, at).
func (l *_List[T]) insertValue(v T, at *_Element[T]) *_Element[T] {
	return l.insert(&_Element[T]{Value: v}, at)
}

// remove removes e from its list, decrements l.len, and returns e.