pub trait RelativeCircularLinkedList<T: Num>: RelativeLinkedList<T> {
fn attach_before(&mut self, head: T, base_element: T, new_element: T) { ... }
fn attach_after(&mut self, head: T, base_element: T, new_element: T) { ... }
fn attach_as_first(&mut self, head: T, element: T) { ... }
fn attach_as_last(&mut self, head: T, element: T) { ... }
fn detach(&mut self, head: T, element: T) { ... }
}