public function getNavHTML($content_label){
		if( !$this->root ){
			return '';
		}
		$landmarks = '';
		$toc = '';
		foreach( $this->children as $child ){
			$toc .= $this->makeList($child, false);
			$landmarks .= $this->makeList($child, true, $content_label);
		}
		$html = <<<HTML
<nav epub:type="toc" id="toc">
	<ol>
		{$toc}
	</ol>
</nav>

<nav id="landmarks" epub:type="landmarks" hidden="hidden" class="hidden">
	<ol epub:type="list">
		{$landmarks}
	</ol>
</nav>
HTML;
		return trim($html);
	}
public function getNavHTML($content_label){
		if( !$this->root ){
			return '';
		}
		$landmarks = '';
		$toc = '';
		foreach( $this->children as $child ){
			$toc .= $this->makeList($child, false);
			$landmarks .= $this->makeList($child, true, $content_label);
		}
		$html = <<<HTML
<nav epub:type="toc" id="toc">
	<ol>
		{$toc}
	</ol>
</nav>

<nav id="landmarks" epub:type="landmarks" hidden="hidden" class="hidden">
	<ol epub:type="list">
		{$landmarks}
	</ol>
</nav>
HTML;
		return trim($html);
	}
public function getNavHTML ( $ content_label ) { if ( ! $ this -> root ) { return '' ; } $ landmarks = '' ; $ toc = '' ; foreach ( $ this -> children as $ child ) { $ toc .= $ this -> makeList ( $ child , false ) ; $ landmarks .= $ this -> makeList ( $ child , true , $ content_label ) ; } $ html =  <<<HTML
<nav epub:type="toc" id="toc">
	<ol>
		{$toc}
	</ol>
</nav>

<nav id="landmarks" epub:type="landmarks" hidden="hidden" class="hidden">
	<ol epub:type="list">
		{$landmarks}
	</ol>
</nav>
HTML ; return trim ( $ html ) ; }
Get navigation html

@param string $content_label
@return string
Get navigation html