def from_filename(self, filename):
        """Return the most appropriate Response class from a file name"""
        mimetype, encoding = self.mimetypes.guess_type(filename)
        if mimetype and not encoding:
            return self.from_mimetype(mimetype)
        else:
            return Response
Return the most appropriate Response class from a file name
stackoverflow/venv/lib/python3.6/site-packages/scrapy/responsetypes.py