{"ast_node_type":"variable","tokens":[{"end":77,"kind":"keyword","start":0,"text":"let"}]}
    let impl_m = tcx.opt_associated_item(impl_m_def_id.to_def_id()).unwrap();
) -> Result<&'tcx DefIdMap<ty::EarlyBinder<'tcx, Ty<'tcx>>>, ErrorGuaranteed> {
    let trait_m = tcx.opt_associated_item(impl_m.trait_item_def_id.unwrap()).unwrap();