{"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"if"}]}
                    if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind()
                    // x's type is '& mut Y' and it is used in `fn generic<T>(x: T) {}`.
                        && arg_param.is_some()