{"ast_node_type":"variable","tokens":[{"end":41,"kind":"keyword","start":0,"text":"let"}]}
    let Ok((trait_bounds, impl_bounds)) =
    //    or `tests/ui/impl-trait/in-trait/refine-normalize.rs` to be refining.
        ocx.deeply_normalize(&ObligationCause::dummy(), param_env, (trait_bounds, impl_bounds))