BEGIN {
   no strict 'refs';
   no warnings 'uninitialized';
   printf("package %s\n", __PACKAGE__);
   for (qw( unit_id )) {
      printf("%s: exists:%s defined:%s prototype:%s\n",
         $_,
         exists(&{$_}) || 0,
         defined(&{$_}) || 0,
         prototype($_),
      );
   }
}