+ /// **What it does:** Checks for unused labels.
+ ///
+ /// **Why is this bad?** Maybe the label should be used in which case there is
+ /// an error in the code or it should be removed.
+ ///
+ /// **Known problems:** Hopefully none.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// fn unused_label() {
+ /// 'label: for i in 1..2 {
+ /// if i > 4 { continue }
+ /// }
+ /// ```