if (in == null) {
            throw new CrawlerSystemException("The inputstream is null.");
        }
        try {
            @SuppressWarnings("resource")
            final SlideShowExtractor<HSLFShape, HSLFTextParagraph> extractor = new SlideShowExtractor<>(new HSLFSlideShow(in));
            return new ExtractData(extractor.getText());
        } catch (final IOException e) {
            throw new ExtractException(e);
        }
    }