You can use Deparse to see the tree for a piece of code

I think you meant to say you can use Concise:

$ perl -MO=Concise -e '$a+$b'
6  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
5     <2> add[t1] vK/2 ->6
-        <1> ex-rv2sv sK/1 ->4
3           <$> gvsv(*a) s ->4
-        <1> ex-rv2sv sK/1 ->5
4           <$> gvsv(*b) s ->5
-e syntax OK
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Dave.