def sum(lst, var=0): """Returns the sum of the list usng recursion.""" if len(lst) == 0: return var #base case return sum(lst[2:], var + lst[0])

The function takes in a list and a variable and returns the sum of the list. It has a two base cases if the list is empty it returns 0 and if the list has only 1 element it returns the element.