Method iter

code/chapter03/linked_list.rs:71–73

(&self)

    }

    pub fn iter(&self) -> Iter<T> {
        Iter { next: self.head.as_deref() }
    }

    pub fn iter_mut(&mut self) -> IterMut<T> {
        IterMut { next: self.head.as_deref_mut() }