could you show an example, please?

perl -MO=Concise FILE will show you the OP tree.

NB: the tree doesn't mean the order of execution, you have to read the line numbers.

C:\>perl.exe -MO=Concise -e"map {$_++} 1..3"
d  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
7     <|> mapwhile(other->8)[t5] vK ->d
6        <@> mapstart K ->7
3           <0> pushmark s ->4
-           <1> null lK/1 ->4
-              <1> null lK/1 ->7
c                 <@> leave lKP ->7
8                    <0> enter l ->9
9                    <;> nextstate(main 2 -e:1) v:{ ->a
b                    <1> postinc[t2] sK/1 ->c
-                       <1> ex-rv2sv sKRM/1 ->b
a                          <#> gvsv[*_] s ->b
5           <1> rv2av lKPM/1 ->6
4              <$> const[AV ] s ->5
-e syntax OK
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more options in B::Concise