public function inCountries(array $req_countries)
    {
        $countries = new ArrayCollection();

        foreach ($req_countries as $country) {
            if ($country = trim($country) === '') {
                continue;
            }
            if ($countries->contains($country)) {
                continue;
            }

            $countries->add($country);
        }

        if (!$countries->isEmpty()) {
            $this->countries = $countries;
        }

        return $this;
    }