{"ast_node_type":"other","tokens":[{"end":68,"kind":"keyword","start":0,"text":"ByRef::Yes(Mutability::Mut)"}]}
                    ByRef::Yes(Mutability::Mut) => inner_mutability,
                    // When `ref mut`, stay a `ref mut` (on `&mut`) or downgrade to `ref` (on `&`).
                    // Once a `ref`, always a `ref`.