public function setMinChoices($minChoices)
    {
        if (is_int($minChoices) === true && ($minChoices > 0 || $minChoices === -1)) {

            if ($minChoices > count($this->getSimpleChoices())) {
                $msg = "The value of 'minChoices' cannot exceed the number of available choices.";
                throw new InvalidArgumentException($msg);
            }

            $this->minChoices = $minChoices;
        } else {
            $msg = "The 'minChoices' argument must be a strictly positive (> 0) integer or -1, '" . gettype($minChoices) . "' given.";
            throw new InvalidArgumentException($msg);
        }
    }