{"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"=>"}]}
                  => $iitem:ident: $imode:tt [$( $ivar:ident: $ityp:ty ),*]
        items [$($( #[$imeta:meta] )*
                                {$( $ifuncs:tt )*} )* ]