input: Write a function to get the maximum and minimum values in a given list. The function should return a tuple containing the minimum value at the first position and the maximum value at the second position. If the list is empty, the function should return (None, None).
  assert get_max_min([3, 4, 5, 1, 2]) == (1, 5)
  assert get_max_min([10, 2, 8, 4, 6]) == (2, 10)
  assert get_max_min([-5, -10, 0, -1]) == (-10, 0)
  assert get_max_min([100]) == (100, 100)
  assert get_max_min([]) == (None, None)
output: def get_max_min(lst):
      if not lst:
          return (None, None)
      return (min(lst), max(lst))