C:\temp>perl -MO=Concise -e "$a='z'" >z
-e syntax OK

C:\temp>cat z
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 "z"] s ->4
-        <1> ex-rv2sv sKRM*/1 ->5
4           <#> gvsv[*a] s ->5

C:\temp>perl -MO=Concise -e "$a='9'" >9
-e syntax OK

C:\temp>diff z 9
5c5
< 3        <$> const[PV "z"] s ->4
---
> 3        <$> const[PV "9"] s ->4