{"ast_node_type":"variable","tokens":[{"end":55,"kind":"keyword","start":0,"text":"let"}]}
        let pred = WhereClause::Implemented(trait_ref);
        let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
        clauses.push(pred.cast::<ProgramClause>(Interner).into_from_env_clause(Interner));