"ser1 = Series([0, 1, 2], index=['Q', 'X', 'Y'])\n", "ser2 = Series([4, 5, 6], index=['X', 'Y', 'Z'])\n", ...
"We can return to a multi-index, if we want to, by setting the index to the two fields to be combined. Whether a multi-index is preferred or not will depend on what you wish to do with the dataframe, ...