{"ast_node_type":"variable","tokens":[{"end":51,"kind":"keyword","start":0,"text":"let"}]}
    let generic_params = generics(db, generic_def);
    let generic_def = GenericDefId::from_callable(db, callable_def);
    let (sig, binders) = db.callable_item_signature(callable_def).into_value_and_skipped_binders();