The returned DataFrame's rows should be sorted in descending order according to the

combined$\_$departure$\_$return$\_$count values $($i$.$e$.,$ the station with the highest total usage

should be in the first row of the returned DataFrame$).$

Example usage

Union Station

Sherbourne St $/$ Wellesley St E

Bay St $/$ College St $($East Side$)$

Princess St $/$ Adelaide St E

Dundas St $\frac{W}{?}$ Yonge $5t$

Part $3-$ Average trip length by membership status

In this part, you will complete the average$\_$trip$\_$duration$\_$by$\_$membership function. This

function will compute the average trip length for both members and non$-$members $($labeled as

"Casual" under the user$\_$type column$)$ during each year and quarter in the dataset.

The function will accept a single DataFrame input, bi keshare$\_$df$,$ which will be formatted like

the DataFrame returned by the function in part $1.$

The function should return a DataFrame with the following columns: