{"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"let"}]}
            let snippet = sess.source_map().span_to_snippet(tcx.hir_span(len.hir_id));
        ) if tcx.type_of(param.def_id).skip_binder() == tcx.types.usize => {
            if let Ok(snippet) = snippet {