wp_sprintf_l( string $pattern, array $args )

function wp_sprintf_l( $pattern, $args ) {
	// Not a match
	if ( substr($pattern, 0, 2) != '%l' )
		return $pattern;

	// Nothing to work with
	if ( empty($args) )
		return '';

	/**
	 * Filters the translated delimiters used by wp_sprintf_l().
	 * Placeholders (%s) are included to assist translators and then
	 * removed before the array of strings reaches the filter.
	 *
	 * Please note: Ampersands and entities should be avoided here.
	 *
	 * @since WP-2.5.0
	 *
	 * @param array $delimiters An array of translated delimiters.
	 */
	$l = apply_filters( 'wp_sprintf_l', array(
		/* translators: used to join items in a list with more than 2 items */
		'between'          => sprintf( __('%s, %s'), '', '' ),
		/* translators: used to join last two items in a list with more than 2 times */
		'between_last_two' => sprintf( __('%s, and %s'), '', '' ),
		/* translators: used to join items in a list with only 2 items */
		'between_only_two' => sprintf( __('%s and %s'), '', '' ),
	) );

	$args = (array) $args;
	$result = array_shift($args);
	if ( count($args) == 1 )
		$result .= $l['between_only_two'] . array_shift($args);
	// Loop when more than two args
	$i = count($args);
	while ( $i ) {
		$arg = array_shift($args);
		$i--;
		if ( 0 == $i )
			$result .= $l['between_last_two'] . $arg;
		else
			$result .= $l['between'] . $arg;
	}
	return $result . substr($pattern, 2);
}