Faker\Factory::getProviderClassname PHP Method

    protected static function getProviderClassname($provider, $locale = '')
    {
        if ($providerClass = self::findProviderClassname($provider, $locale)) {
            return $providerClass;
        }
        // fallback to default locale
        if ($providerClass = self::findProviderClassname($provider, static::DEFAULT_LOCALE)) {
            return $providerClass;
        }
        // fallback to no locale
        if ($providerClass = self::findProviderClassname($provider)) {
            return $providerClass;
        }
        throw new \InvalidArgumentException(sprintf('Unable to find provider "%s" with locale "%s"', $provider, $locale));
    }