"[ [ $a, 12], [$b, 1.2], [ $c, [ $aaa, $bbb, $ccc ] ], [ $torun, #first ] ]" perform .s
[1] (List) [[a, 12], [b, 1.2], [c, [aaa, bbb, ccc]], [torun, #first]]

"12 13 +" perform
[1:interpreter] ExCompiler : Can't evaluate <+>