{"ast_node_type":"other","tokens":[{"end":55,"kind":"keyword","start":0,"text":".with_type_param_mode(ParamLoweringMode::Variable);"}]}
    .with_type_param_mode(ParamLoweringMode::Variable);
    .with_impl_trait_mode(ImplTraitLoweringMode::Disallowed)
    let mut idx = 0;