private function parseShellArgument($token, $rest)
    {
        $c = \count($this->arguments);

        // if input is expecting another argument, add it
        if ($this->definition->hasArgument($c)) {
            $arg = $this->definition->getArgument($c);

            if ($arg instanceof CodeArgument) {
                // When we find a code argument, we're done parsing. Add the
                // remaining input to the current argument and call it a day.
                $this->parsed = [];
                $this->arguments[$arg->getName()] = $rest;
            } else {
                $this->arguments[$arg->getName()] = $arg->isArray() ? [$token] : $token;
            }

            return;
        }

        // (copypasta)
        //
        // @codeCoverageIgnoreStart

        // if last argument isArray(), append token to last argument
        if ($this->definition->hasArgument($c - 1) && $this->definition->getArgument($c - 1)->isArray()) {
            $arg = $this->definition->getArgument($c - 1);
            $this->arguments[$arg->getName()][] = $token;

            return;
        }

        // unexpected argument
        $all = $this->definition->getArguments();
        if (\count($all)) {
            throw new \RuntimeException(\sprintf('Too many arguments, expected arguments "%s".', \implode('" "', \array_keys($all))));
        }

        throw new \RuntimeException(\sprintf('No arguments expected, got "%s".', $token));
        // @codeCoverageIgnoreEnd
    }