2_cust_churn_train_deploy_infer.ipynb failed CI

Link to the notebook:
https://github.com/aws/amazon-sagemaker-examples/blob/master/use-cases/customer_churn/2_cust_churn_train_deploy_infer.ipynb

Error:

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Exception encountered at "In [7]":
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NameError Traceback (most recent call last)
in
2
3 content_type = "csv"
----> 4 train_input = TrainingInput("s3://{}/{}/{}/".format(bucket, prefix, 'train'), content_type=content_type)
5 validation_input = TrainingInput("s3://{}/{}/{}/".format(bucket, prefix, 'validation'), content_type=content_type)

NameError: name 'bucket' is not defined

Open 2_cust_churn_train_deploy_infer.ipynb and inspect the cells before In [7] to determine where bucket should be defined. Rerun the notebook or its CI validation and confirm that the training inputs execute without the reported NameError.

Written by the indexing model from the issue text.