> perl -E '
use P;
for  ($_=3;$_-- >0;) { P "_=%s", $_ }'    
_=2
_=1
_=0

##</code><code>##

> perl -E '
use P;
P "_=%s", $_ for $_=3;$_-- >0; '
_=3

##</code><code>##

> perl -E '
use P;
$_=1;
P "_=$_" if --$_;
> P "got to end w/_=%s", $_;
> '
got to end w/_=0

#alternatively:
> perl -E '
use P;
$_=12;
P "_=$_" if --$_;
P "got to end w/_=%s", $_;
'
_=11
got to end w/_=11