{"ast_node_type":"variable","tokens":[{"end":84,"kind":"keyword","start":0,"text":"let"}]}
        let output_is_sized_pred = tupled_inputs_and_output_and_coroutine.map_bound(
        // (FIXME: technically we only need to check this if the type is a fn ptr...)
            |AsyncCallableRelevantTypes { output_coroutine_ty: output_ty, .. }| {