The file P$02\_56.$xlsx contains monthly values of indexes that measure the amount of energy necessary to heat or cool buildings due to outside temperatures. $($See the explanation in the Source sheet of the file.$)$ These are reported for each state in the United States and also for several regions, as listed in the Locations sheet, from $1931$ to $2000.$ For each of the Heating Degree Days and Cooling Degree Days sheets, create a new Season variable with values "Winter," "Spring," "Summer," and "Fall."

a$.$ Winter: $($Dec$,$ Jan, Feb$)$

b$.$ Spring: $($Mar$,$ Apr, May$)$

c$.$ Summer: $($Jun$,$ Jul, Aug$)$

d$.$ Fall: $($Sep$,$ Oct, Nov$)$