sub Node::climb_up {
  my ($self, $proc) = @_;
  my ($magic, @return);
  my $return_onTop = sub { @return = @_; die \$magic; };

  COND_CLIMB: while ( $self = $self->parent_row ) {
    eval { @return = $proc->($self, $return_onTop) };
    if ( $@ ) { $@ == \$magic ? next : die $@; }
    else { last COND_CLIMB; }
  }

  return @return;
}