Wie is this Index with multiple keys

Hello community,

how can i change this Further Warning?

Indexing with multiple keys (implicitly converted to a tuple of keys) will be deprecated, use a list instead.

It´s for this line of code:
summe2 = round(dff.groupby(monat_week, as_index=False)[‘Umsatz’, ‘Anzahl’].agg(“sum”),2)

I solved my problem