>perl -MO=Concise -e"<FH>"
5  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
4     <1> readline[t2] vK/1 ->5
3        <#> gv[*FH] s ->4
-e syntax OK

>perl -MO=Concise -e"readline(*FH)"
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
5     <1> readline[t2] vK/1 ->6
4        <1> rv2gv sKR/1 ->5
3           <#> gv[*FH] s ->4
-e syntax OK