> perl -MO=Deparse tst.pl
sub BEGIN {
    sub MyPackg::Debug {
        0;
    }
    
}
our $a = 1;
package MyPackg;
sub BEGIN {
    require constant;
    do {
        'constant'->import('DBG', Debug())
    };
}
'???';
print 'huhu';
tst.pl syntax OK