how to drop columns where only all values are nans in python

main.py
import pandas as pd

# create a sample dataframe
df = pd.DataFrame({'A': [1, 2, np.nan], 'B': [np.nan, np.nan, np.nan], 'C': [3, 4, np.nan]})

# drop columns where all values are nan
df.dropna(axis=1, how='all', inplace=True)

print(df)
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main.py
     A    C
 0  1.0  3.0
 1  2.0  4.0
 2  NaN  NaN
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