return None

    def _create_credentials_fetcher(self):
        method = self.METHOD

        def fetch_credentials():
            # HTTP headers are case insensitive filter out
            # all duplicate headers and pick one.
            headers = {}
            headers['content-type'] = 'application/x-www-form-urlencoded'
            headers['authorization'] = urllib3.make_headers(

                                 config=Config(signature_version='s3v4'),
                                 region_name='us-east-1')

    bucket = s3_resource.Bucket('testbucket')

    for obj in bucket.objects.all():
        print(obj)

    return "success"


if __name__ == '__main__':