df[df.isnull().any(axis=1)]
df.isnull().values.any()
df['column_1'].fillna(df['column_2'], inplace=True)
df[df['col'].isnull()]
df['your column name'].isnull().sum()
df['your column name'].isnull().values.any()
# to mark NaN column as True
df['your column name'].isnull()
df['your column name'].isnull().values.any()
df.isnull().sum().sum()
df['your column name'].isnull()
df[df["A_col"].isnull()]