$ perl -MO=Concise -e'pop @a'
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
5     <1> pop vK/1 ->6
4        <1> rv2av[t2] lKRM/1 ->5       <-- "l"ist context.
3           <#> gv[*a] s ->4
-e syntax OK