# perl -MO=Concise -e '$s = "a" x 3';
8  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
7     <2> sassign vKS/2 ->8
5        <2> repeat[t2] sK/2 ->6
3           <$> const[PV "a"] s ->4
4           <$> const[IV 3] s ->5
-        <1> ex-rv2sv sKRM*/1 ->7
6           <#> gvsv[*s] s ->7