Groupby multiple columns then overlay without naming columns twice

HoloViews
1

Current code:

# df is a dataframe with columns x,y,a,b
hv.HoloMap(
    {k:hv.Curve(v,'x','y') for k,v in df.groupby(['a','b'])},
    kdims=['a','b']
).overlay()

Is there any way to avoid repeating myself with the column names?