df.loc[slice(pd.Timestamp('2012-01-01 12:12:12'), pd.Timestamp(
    '2012-01-03 12:12:12'))]
df.loc[slice(pd.Timestamp('2012-01-01 12:12:12'), pd.Timestamp(
    '2012-01-03 12:12:12')), slice(None)]
slicing a pandas multiindex using datetime datatype