gistfile1.phtml

<?php

class i18n
{
    private static $strings = [
        'WELCOME' => [
            'en' => 'Welcome',
            'es' => 'Bienvenidos',
        ],
    ];
    
    public static function str($string)
    {
        if (isset(self::$strings[$string]))
        {
            return self::$strings[$string];
        }
        else
        {
            throw Exception('That string doesn’t exist');
        }
    }
}

?>

<h1><?= i18n::str('WELCOME'); ?>