{"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"let"}]}
                let mut p = FmtPrinter::new(self.tcx, Namespace::ValueNS);
            let fmt_valtree = |cv: &ty::Value<'tcx>| {
                p.pretty_print_const_valtree(*cv, /*print_ty*/ true).unwrap();