{"ast_node_type":"variable","tokens":[{"end":59,"kind":"keyword","start":0,"text":"let"}]}
        let mut args = vec![GenericArgKind::Type(self_ty)];
    pub fn new(def_id: TraitDef, self_ty: Ty, gen_args: &GenericArgs) -> TraitRef {
        args.extend_from_slice(&gen_args.0);