{"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"parenthesized:"}]}
            parenthesized: hir::GenericArgsParentheses::No,
            constraints: arena_vec![self; self.assoc_ty_binding(assoc_ty_name, opaque_ty_span, output_ty)],
            span_ext: DUMMY_SP,