>perl -MO=Concise -e"@a=(1,(2,3,(4,5)),6,7)"
j  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
i     <2> aassign[t3] vKS ->j
-        <1> ex-list lKP ->f
3           <0> pushmark s ->4
4           <$> const[IV 1] s ->5
c           <@> list lKP ->d             <-- This list...
5              <0> pushmark s ->6
6              <$> const[IV 2] s ->7
7              <$> const[IV 3] s ->8
b              <@> list lKP ->c          <-- ...has a list for operand
8                 <0> pushmark s ->9
9                 <$> const[IV 4] s ->a
a                 <$> const[IV 5] s ->b
d           <$> const[IV 6] s ->e
e           <$> const[IV 7] s ->f
-        <1> ex-list lK ->i
f           <0> pushmark s ->g
h           <1> rv2av[t2] lKRM*/1 ->i
g              <#> gv[*a] s ->h
-e syntax OK