Write a function in python named reverse_list that takes as a parameter a list and reverses the order of the elements in that list. It should not return anything - it should mutate the original list. This can be done trivially using slices, but your function must not use any slicing (you may use indexing, but not slicing).

Your function could be used like this: vals = [7, -3, 12, 9] reverse_list(vals) print(vals) # This should print [9, 12, -3, 7]