"""
        if self.cid is not None:
            fetcher = self._create_credentials_fetcher()
            return RefreshableCredentials.create_from_metadata(
                metadata=fetcher(),
                refresh_using=fetcher,
                method=self.METHOD,
            )
        else:
            return None

    def _create_credentials_fetcher(self):
        method = self.METHOD

        def fetch_credentials():

# Upload with server side encryption, using temporary credentials
s3.meta.client.upload_file('/etc/hosts',
                           'testbucket',
                           'hosts',
                           ExtraArgs={'ServerSideEncryption': 'AES256'})

# Download encrypted object using temporary credentials