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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def serve_file(self, private_file):
 """ Serve the file that was retrieved from the storage. The relative path can be found with ``private_file.relative_name``. :type private_file: :class:`private_storage.models.PrivateFile` :rtype: django.http.HttpResponse """

        response = self.server_class().serve(private_file)

        if self.content_disposition:
            # Join syntax works in all Python versions. Python 3 doesn't support b'..'.format(),
            # and % formatting was added for bytes in 3.5: https://bugs.python.org/issue3982
            filename = self.get_content_disposition_filename(private_file)
            response['Content-Disposition'] = b'; '.join([
                self.content_disposition.encode(), self._encode_filename_header(filename)
            ])

        return response