public static function env(string $variable = null, $default = null)
    {
        // If there was no variable requested
        if (null === $variable) {
            // Return the env class
            return static::getEnv();
        }

        // If the env has this variable defined and the variable isn't null
        if (
            \defined(static::getEnv() . '::' . $variable)
            && null !== $env = \constant(static::getEnv() . '::' . $variable)
        ) {
            // Return the variable
            return $env;
        }

        // Otherwise return the default
        return $default;
    }