在多索引 Pandas Dataframe 上使用 Natsort

Question

I have the following DF which is multi-index due to using groupby():

date	code	quarter	average
20201231	ABCD	Q1	3135
		Q10	3135
		Q11	3135
		Q12	3135
		Q2	3135

I'm trying to sort by date, code and then quarter which are part of the multi-index, however I want to use a Natsort method such that the order is Q1, Q2, ....Q9, Q10... but get various errors when I try do so. My best attempt is:

df.sort_index(level=['date','code','quarter'], ascending=[True, True, True], key=natsort_keygen())

I receive the following error:

NotImplementedError: isna is not defined for MultiIndex

I'm using Pandas version 1.1.5, Natsort 8.1.0, Python 3.6.9