BEGIN {
    sub MyPackg::DBG() {
        0;
    }
    
}
our $a = 1;
package MyPackg;
print 'DEBUGGING' if DBG();  # <-- oops
print 'huhu';

##</code><code>##

F:\>perl -MO=Deparse tmp.pl
sub MyPackg::DBG () { 0 }
sub BEGIN {

}
our $a = 1;
package MyPackg;
'???';
print 'huhu';
tmp.pl syntax OK