{"ast_node_type":"variable","tokens":[{"end":81,"kind":"keyword","start":0,"text":"let"}]}
        let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
    fn location_triple_for_span(&self, span: Span) -> (Symbol, u32, u32) {
        let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());