get_post_time

	 * @param string $the_modified_date The last modified date.
	 * @param string $format            PHP date format. Defaults to 'date_format' option
	 *                                  if not specified.
	 * @param string $before            HTML output before the date.
	 * @param string $after             HTML output after the date.
	 */
	$the_modified_date = apply_filters( 'the_modified_date', $the_modified_date, $format, $before, $after );

	if ( $echo ) {
		echo $the_modified_date;
	} else {
		return $the_modified_date;
	}

}

/**
 * Retrieve the date on which the post was last modified.
 *
 * @since 2.1.0
 * @since 4.6.0 Added the `$post` parameter.
 *
 * @param string      $format Optional. PHP date format defaults to the date_format option if not specified.
 * @param int|WP_Post $post   Optional. Post ID or WP_Post object. Default current post.
 * @return string|false Date the current post was modified. False on failure.
 */
function get_the_modified_date( $format = '', $post = null ) {
	$post = get_post( $post );

	if ( ! $post ) {
		// For backward compatibility, failures go through the filter below.
		$the_time = false;
	} else {
		$_format = ! empty( $format ) ? $format : get_option( 'date_format' );

		$the_time = get_post_modified_time( $_format, false, $post, true );
	}

	/**
	 * Filters the date a post was last modified.
	 *
	 * @since 2.1.0
	 * @since 4.6.0 Added the `$post` parameter.