>perl -MO=Concise,f -e"sub f { return ($x,$y) }"
main::f:
6  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->6
1        <;> nextstate(main 1 -e:1) v ->2
5        <@> return KP ->6
2           <0> pushmark s ->3
-           <1> ex-rv2sv sK/1 ->4
3              <#> gvsv[*x] s ->4
-           <1> ex-rv2sv sK/1 ->5
4              <#> gvsv[*y] s ->5
-e syntax OK

>perl -MO=Concise,f -e"sub f { ($x,$y) }"
main::f:
6  <1> leavesub[1 ref] K/REFC,1 ->(end)
-     <@> lineseq KP ->6
1        <;> nextstate(main 1 -e:1) v ->2
5        <@> list KP ->6
2           <0> pushmark s ->3
-           <1> ex-rv2sv sK/1 ->4
3              <#> gvsv[*x] s ->4
-           <1> ex-rv2sv sK/1 ->5
4              <#> gvsv[*y] s ->5
-e syntax OK