{"ast_node_type":"variable","tokens":[{"end":91,"kind":"keyword","start":0,"text":"let"}]}
                let ty = wfcx.deeply_normalize(span, Some(WellFormedLoc::Ty(item_id)), ty);
                let ty = tcx.type_of(item.def_id).instantiate_identity();
                wfcx.register_wf_obligation(span, loc, ty.into());