I want to Mutate a column h, which contains respective column names [A,B,C,D] if it contains 1
import pandas as pd
dfz = pd.DataFrame({'A' : [1,0,0,1,0,0],
'B' : [1,0,0,1,0,1],
'C' : [1,0,0,1,3,1],
'D' : [1,0,0,1,0,0]})
dfz['h'] = dfz.loc[:, 'A':'D'].replace(1,pd.Series(dfz.columns,dfz.columns))
Expected output