{"ast_node_type":"other","tokens":[{"end":100,"kind":"keyword","start":0,"text":"opaque_types:"}]}
            opaque_types: self.opaque_types.iter().map(|opaque| opaque.fold_with(folder)).collect(),
        TypeFolder::cx(folder).mk_predefined_opaques_in_body(PredefinedOpaquesData {
        })