{"ast_node_type":"variable","tokens":[{"end":87,"kind":"keyword","start":0,"text":"let"}]}
                    let index = generics.param_def_id_to_index[&param_def_id] as usize;
                    // This index can be used with `generic_args` since `parent_count == 0`.
                    generic_args.args.get(index).and_then(|arg| match arg {