list my categories function

list_my_categories(); function

function list_my_categories(){
  $categories = get_categories('parent=0');
	$html = '';

	foreach ($categories as $q_cat) {
		$cat = get_category($q_cat);

		$html .= '<div class="span12 service_container"><div class="row">';
		// category parent
		$html .= '<div id="piscinaProduct" class="span12 product_block product_name_title_active">';
		$html .= '<h2 class="product_name_title main_title">'.$cat->cat_name.'</h2>';
		$html .= '</div>';//end category parent
		$html .= '<div class="span12 subCategoria"><div class="row">';

		$categories = get_categories('parent='.$cat->cat_ID);
		foreach ($categories as $q_cat) {
			$cat = get_category($q_cat);
				
			$html .= '<div class="span4 blueBackground service_name">';
			$html .= '<a href="'.$cat->cat_term_id.'">';
			$html .= '<h2 class="product_name_title">'.$cat->cat_name.'</h2>';
			$html .= '</a>';
			$html .= '</div>';
		
		}

		$html .= '</div></div>';//subcategorias
		$html .= '</div></div>';
	}

	$html .= '';
	return $html;
}