Return a UpdateResult object if there is a newer version.

def check(self, package_name, package_version, **extra_data):
        """Return a UpdateResult object if there is a newer version."""
        data = extra_data
        data['package_name'] = package_name
        data['package_version'] = package_version
        data['python_version'] = sys.version.split()[0]
        data['platform'] = platform.platform(True) or 'Unspecified'

        try:
            headers = {'connection': 'close',
                       'content-type': 'application/json'}
            response = requests.put(self.url, json.dumps(data), timeout=1,
                                    headers=headers)
            if response.status_code == codes.UNPROCESSABLE_ENTITY:
                return 'update_checker does not support {!r}'.format(
                    package_name)
            data = response.json()
        except (requests.exceptions.RequestException, ValueError):
            return None

        if not data or not data.get('success') \
                or (parse_version(package_version) >=
                    parse_version(data['data']['version'])):
            return None

        return UpdateResult(package_name, running=package_version,
                            available=data['data']['version'],
                            release_date=data['data']['upload_time'])