mpyw / co

     * @throws InvalidArgumentException

     * @return float

     */

    private static function validateNaturalFloat($key, $value)

    {

        $value = filter_var($value, FILTER_VALIDATE_FLOAT);

        if ($value === false || $value < 0.0) {

            throw new \InvalidArgumentException("Option[$key] must be positive float or zero.");

        }

        return $value;

    }

    /**

     * Validate natural int value.

     * @throws InvalidArgumentException

     * @return int

     */

    private static function validateNaturalInt($key, $value)

    {

        $value = filter_var($value, FILTER_VALIDATE_INT);

        if ($value === false || $value < 0) {

            throw new \InvalidArgumentException("Option[$key] must be positive integer or zero.");

        }

        return $value;

    }

}