At the JPY Notebooks in the Hands on with Data Science Course I had a problem with the execution of the notepad and I managed to fix it by changing the attribute related to the dataframe.

“Data_processing_and_analysis_for_IDA_course.ipynb”
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# How many timeseries are missing externalId?

## Instead of len(all_timeseries_is_null[all_timeseries_is_null.externalId == True]) use the bellow sentence

len(all_timeseries_is_null[all_timeseries_is_null.unit == True])

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