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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 __upload(self, resource, bytes):
 """Performs a single chunk upload."""


        # note: string conversion required here due to open encoding bug in requests-oauthlib.
        headers = {
            'x-ton-expires': http_time(self.options.get('x-ton-expires', self._DEFAULT_EXPIRE)),
            'content-length': str(self._file_size),
            'content-type': self.content_type
        }

        return Request(self._client, 'post', resource,
                       domain=self._DEFAULT_DOMAIN, headers=headers, body=bytes).perform()