#in scala

Write a function reduce that takes in two parameters: a function f that takes in two Ints and returns an Int, and a list xs of Ints. You should use the function f to combine all of the elements of the list. For instance, if I have a list and a function as follows:

def ls = 7::2::5::1::Nil

def add(x:Int, y:Int) = x+y

then reduce(add, ls) would return 7+2+5+1= 15. Ensure that your function would also do the right thing if called with a function that multiplied two inputs.