input: Write a python function to find the minimum and maximum numbers in a list.
  assert find_min_max([10, 24, 55, 16, 1, 9]) == (1, 55)
  assert find_min_max([100, 200, 300, 400, 500]) == (100, 500)
  assert find_min_max([5, -2, 3, 0, 12]) == (-2, 12)
output: def find_min_max(numbers):
      if not numbers:
          return (None, None)
      min_num = min(numbers)
      max_num = max(numbers)
      return (min_num, max_num)