/// force this degenerate behaviour to occur on every operation. While the total amount of work
/// done on each operation isn't *catastrophic*, and *is* still bounded by O(B log<sub>B</sub>n),
/// it is certainly much slower when it does.
-#[deriving(Clone)]
+#[derive(Clone)]
#[stable]
pub struct BTreeMap<K, V> {
root: Node<K, V>,