I have a DataFrame
import pandas as pd
import numpy as np
index = pd.MultiIndex.from_product([["A", "B"], ["AA", "BB"]])
columns = pd.MultiIndex.from_product([["X", "Y"], ["XX", "YY"]])
df = pd.DataFrame([[1,2,3,4],
[5,6,7,8],
[9,10,11,12],
[13,14,15,16]], index = index, columns = columns)
and a slice slice_ = ((slice(None), slice(None)), ("X", "XX")). Unfortunately df.loc[slice_] returns Series instead DataFrame. How can I fix that?