_navigation_markup

 * @since 4.1.0
 * @since 5.3.0 Added the `aria_label` parameter.
 * @access private
 *
 * @param string $links              Navigational links.
 * @param string $class              Optional. Custom class for the nav element.
 *                                   Default 'posts-navigation'.
 * @param string $screen_reader_text Optional. Screen reader text for the nav element.
 *                                   Default 'Posts navigation'.
 * @param string $aria_label         Optional. ARIA label for the nav element.
 *                                   Defaults to the value of `$screen_reader_text`.
 * @return string Navigation template tag.
 */
function _navigation_markup( $links, $class = 'posts-navigation', $screen_reader_text = '', $aria_label = '' ) {
	if ( empty( $screen_reader_text ) ) {
		$screen_reader_text = __( 'Posts navigation' );
	}
	if ( empty( $aria_label ) ) {
		$aria_label = $screen_reader_text;
	}

	$template = '
	<nav class="navigation %1$s" role="navigation" aria-label="%4$s">
		<h2 class="screen-reader-text">%2$s</h2>
		<div class="nav-links">%3$s</div>
	</nav>';

	/**
	 * Filters the navigation markup template.
	 *
	 * Note: The filtered template HTML must contain specifiers for the navigation
	 * class (%1$s), the screen-reader-text value (%2$s), placement of the navigation
	 * links (%3$s), and ARIA label text if screen-reader-text does not fit that (%4$s):
	 *
	 *     <nav class="navigation %1$s" role="navigation" aria-label="%4$s">
	 *         <h2 class="screen-reader-text">%2$s</h2>