# Your code
# Pure
sub walk_and_do
{
    my $self = shift;

    my $rc = 1;
    foreach my $child (@{$self->children})
    {
        $rc = $child->walk_and_do;
        last unless $rc;
    }

    unless ($rc)
    {
        $rc = $self->do_my_stuff;
    }

    return $rc;
}

# Same function, single return, just as clear (for me)
# ala TIMTOWTDI
sub walk_and_do {
   my($self,$flag,@return);
   
   $self = shift;

   for ( @{$self->childer} ) {
      (last && $flag = "$_->{err}") unless $_->walk_and_do;
   }

   if ($flag) {
      @return = ('0', "$flag);

   } else {
      @return = $self->do_my_stuff || ('0', $self->{err});
   }

   return(@return);
      
}# END sub walk_and_do