protected function parseOptions(string $arg, string $nextArg = null): bool
    {
        $value = \substr($nextArg, 0, 1) === '-' ? null : $nextArg;

        if (null === $option  = $this->optionFor($arg)) {
            return $this->handleUnknown($arg, $value);
        }

        $this->_lastVariadic = $option->variadic() ? $option->attributeName() : null;

        return false === $this->emit($option->attributeName(), $value) ? false : $this->setValue($option, $value);
    }