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function lista_categorias() {
  ob_start();
  $a = shortcode_atts( array(
		'att' => ''
  ), $atts ); 

  echo '<ul>';
    wp_list_categories( array(
        'orderby'    => 'name',
        'show_count' => false,
        'exclude'    => array( 10 ),
        'title_li' => ''
    ) );
  echo '</ul>' ;

  $content = ob_get_contents();
  ob_end_clean();
  return $content;
}
add_shortcode('lista-categorias', 'lista_categorias');