CI_Form_validation::valid_emails PHP Method

    public function valid_emails($str)
    {
        if (strpos($str, ',') === FALSE) {
            return $this->valid_email(trim($str));
        }
        foreach (explode(',', $str) as $email) {
            if (trim($email) !== '' && $this->valid_email(trim($email)) === FALSE) {
                return FALSE;
            }
        }
        return TRUE;
    }