$ cat foo.pl
use strict;
use warnings;
use constant DEBUG=>0;

print "Foo bar!\n";
print "Baz\n" if DEBUG;

$ perl -MO=Concise,-exec foo.pl
1  <0> enter
2  <;> nextstate(main 191 foo.pl:5) v:*,&,{,x*,x&,x$,$
3  <0> pushmark s
4  <$> const[PV "Foo bar!\n"] s
5  <@> print vK
6  <;> nextstate(main 191 foo.pl:6) v:*,&,{,x*,x&,x$,$
7  <@> leave[1 ref] vKP/REFC
foo.pl syntax OK