Let's find out which exact holiday was the most profitable according to sales. To do this, we will need to replace the dates with respective labels of holidays, so that we can group by a certain holiday. But all of the holidays have different dates in the data, so we need to perform a replacement first and then group by the new values. We have gathered the dates and their respective holidays in the holidays_dates dictionary (keys are dates, and values are the names of the holidays).