public function configure($option, $value)
    {
        // Dumpy won't let you add any custom config options, only update the existing ones.
        if ( ! array_key_exists($option, $this->config)) {
            // Note: something really weird is going to happen if $option is, say, an array.
            throw new InvalidArgumentException("Invalid option name: {$option}");
        }

        // Note that:
        // 1) the passed value can be of any type and contain anything
        // 2) the option value will be overridden permanently, no way back
        $this->config[$option] = $value;
    }