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Traceback (most recent call last):
  File "/home/cloudshell-user/testpy.py", line 42, in <module>
    main()
  File "/home/cloudshell-user/testpy.py", line 34, in main
    combined_df = pd.merge(event_summaries_df, event_details_df, on='arn', suffixes=('_summary', '_details'))
  File "/home/cloudshell-user/.local/lib/python3.9/site-packages/pandas/core/reshape/merge.py", line 170, in merge
    op = _MergeOperation(
  File "/home/cloudshell-user/.local/lib/python3.9/site-packages/pandas/core/reshape/merge.py", line 794, in __init__
    ) = self._get_merge_keys()
  File "/home/cloudshell-user/.local/lib/python3.9/site-packages/pandas/core/reshape/merge.py", line 1297, in _get_merge_keys
    right_keys.append(right._get_label_or_level_values(rk))
  File "/home/cloudshell-user/.local/lib/python3.9/site-packages/pandas/core/generic.py", line 1911, in _get_label_or_level_values
    raise KeyError(key)