input: Write a python function to find the difference between the maximum and minimum values in a list of numbers.
  assert diff_max_min([1, 2, 3, 4, 5]) == 4
  assert diff_max_min([10, 20, 30, 40, 50]) == 40
  assert diff_max_min([5, 5, 5, 5, 5]) == 0
output: def diff_max_min(numbers):
      return max(numbers) - min(numbers)