private function checkPaths()
    {
        if (!is_dir($this->sassPath)) {
            throw new \RuntimeException(sprintf('The path %s do not exists', $this->sassPath));
        }
        if (!is_dir($this->cssPath)) {
            try {
                mkdir($this->cssPath);
            } catch (\Exception $e) {
                throw new \RuntimeException(sprintf('The path %s do not exists, and could not be created', $this->cssPath));
            }
        }
        if (!is_writable($this->sassPath)) {
            throw new \RuntimeException(sprintf('The path %s should be writable (by the webserver user) for CompassElephant to compile the project', $this->sassPath));
        }
        if (!is_writable($this->cssPath)) {
            throw new \RuntimeException(sprintf('The path %s should be writable (by the webserver user) for CompassElephant to compile the project', $this->cssPath));
        }
    }