[Bug Report]

**Link to the notebook**
https://github.com/aws/amazon-sagemaker-examples/blob/main/sagemaker-pipelines/tabular/abalone_build_train_deploy/sagemaker-pipelines-preprocess-train-evaluate-batch-transform.ipynb

**Describe the bug**
Cannot run as is, raised 'TypeError: Pipeline variables do not support __str__ operation. Please use `.to_string()` to convert it to string type in execution timeor use `.expr` to translate it to Json for display purpose in Python SDK.'

**To reproduce**
Run the notebook as is and in cell 24 and onwards, raised the above error

**Logs**
If applicable, add logs to help explain your problem.
You may also attach an `.ipynb` file to this issue if it includes relevant logs or output.

Open the linked sagemaker-pipelines-preprocess-train-evaluate-batch-transform.ipynb notebook and run it as-is, starting with cell 24. Confirm the reported Pipeline variables __str__ TypeError and trace which notebook expression triggers it. Done means the notebook runs past cell 24 and the affected later cells without that error.

Written by the indexing model from the issue text.