How to do left outer join exclusion in pandas

Check out this link

df = pd.merge(dfA, dfB, on=['a','b'], how="outer", indicator=True)
df = df[df['_merge'] == 'left_only']

One liner :

df = pd.merge(dfA, dfB, on=['a','b'], how="outer", indicator=True
              ).query('_merge=="left_only"')

I think it would go something like the examples in: Pandas left outer join multiple dataframes on multiple columns

dfe = pd.merge(dFA, dFB, how='left', on=['a','b'], indicator=True)
dfe[dfe[_merge] == 'left_only']