# perl -MO=Concise -e '$s = "aaa"';
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
5     <2> sassign vKS/2 ->6
3        <$> const[PV "aaa"] s ->4
-        <1> ex-rv2sv sKRM*/1 ->5
4           <#> gvsv[*s] s ->5