runtime error

Exit code: 1. Reason: Traceback (most recent call last): File "/home/user/app/app.py", line 52, in <module> weather_data = prepare_weather_data() File "/home/user/app/app.py", line 46, in prepare_weather_data weather['target'] = weather.groupby('city')['tavg'].shift(-1) File "/usr/local/lib/python3.10/site-packages/pandas/core/frame.py", line 9190, in groupby return DataFrameGroupBy( File "/usr/local/lib/python3.10/site-packages/pandas/core/groupby/groupby.py", line 1329, in __init__ grouper, exclusions, obj = get_grouper( File "/usr/local/lib/python3.10/site-packages/pandas/core/groupby/grouper.py", line 1043, in get_grouper raise KeyError(gpr) KeyError: 'city'

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