use strict;
use warnings;

use XML::Twig;

my $xml = <<XML;
<foo>
      <yahoo V="bay">
          <bay_id>
              <value>1</value>
              <fact>yes</fact>
          </bay_id>
          <bay_seen>
              <value>10</value>
              <fact>no</fact>
          </bay_seen>
          <bay_overall value="disabled"/>
          <bayking_list>
              <bayking id="kingjames" country="usa" active="true">
                  <bayking type="dictator"/>
                  <bay_usage value="none"/>
                  <bayking_origin>
                        <bayking_origin_name value="ohio_usa" emmigrate="no">
                               <economy_status_previous value="very poor" />
                        </bayking_origin_name>
                  </bayking_origin>
              </bayking>
          </bayking_list>
          <bayqueen_list>
              <bayqueen id="queenliz" country="france" active="true">
                  <bayqueen type="dictator"/>
                  <bay_usage value="none"/>
                  <bayqueen_origin>
                        <bayqueen_origin_name value="ohio_usa" emmigrate="no"/>
                  </bayqueen_origin>
              </bayqueen>
          </bayqueen_list>
      </yahoo>
      <yahoo V="baz">
          <bay_id>
              <value>1000</value>
              <fact>yes</fact>
          </bay_id>
          <bay_seen>
              <value>50</value>
              <fact>no</fact>
          </bay_seen>
          <bay_overall value="disabled"/>
          <bayking_list>
              <bayking id="kingtony" country="Russia" active="true">
                  <bayking type="dictator"/>
                  <bay_usage value="none"/>
                  <bayking_origin>
                        <bayking_origin_name value="ohio_usa" emmigrate="no">
                               <economy_status_previous value="very poor" />
                        </bayking_origin_name>
                  </bayking_origin>
              </bayking>
          </bayking_list>
          <bayqueen_list>
              <bayqueen id="queensarah" country="japan" active="true">
                  <bayqueen type="dictator"/>
                  <bay_usage value="none"/>
                  <bayqueen_origin>
                        <bayqueen_origin_name value="ca_usa" emmigrate="no"/>
                               <economy_status_previous value="very poor" />
                               <previous marriage="no"/>
                  </bayqueen_origin>
              </bayqueen>
          </bayqueen_list>
      </yahoo>
</foo>
XML

my $sabal = new XML::Twig(
              twig_roots          => {
                     'foo/yahoo'  =>
                     #'bayking[@id="kingtony"]'   =>
                         sub {
                             my ($yabal, $element ) = @_;
                             if ( $yabal->bayking_list->bayking->att('id') eq 'kingtony' ) {
                                     $element->print;
                             }
                          }
              }
);

$sabal->parse($xml);