input: Write a python function to find the difference between the maximum and minimum values in a list.
  assert getDifference([2, 5, 1, 8, 7]) == 7
  assert getDifference([10, 20, 30, 40, 50]) == 40
  assert getDifference([5, 5, 5, 5]) == 0
  assert getDifference([-10, 0, 10, 20]) == 30
output: def getDifference(lst):
      return max(lst) - min(lst)