{"ast_node_type":"variable","tokens":[{"end":60,"kind":"keyword","start":0,"text":"///"}]}
    /// `let (ref x0, ref x1) = *it;` we should use `Deref`.
    /// mutable. For example in `let (ref mut x0, ref x1) = *it;` we need to use `DerefMut` for `*it` but in
    fn pat_bound_mutability(&self, pat: PatId) -> Mutability {