The counter function counts down from start to stop when start is bigger than stop, and counts up from start to stop otherwise. Fill in the blanks to make this work correctly. 1- def counter(start, stop): X = start if ---: return_string while x >= stop: return_string += str(x) if ---: return_string += 2 3 - 4 "Counting down: 5 - 8 10 - else: "Counting up: return_string while x