input: def get_greatest_2(items: List[int]) -> Tuple[int, int]:
      """
      Given a list of integers, this function returns a tuple containing the two greatest numbers in the list.
      
      >>> get_greatest_2([1, 5, 3, 7, 4, 7, 8, 9, 2, 10, 6, 8])
      (10, 9)
      >>> get_greatest_2([1, 2, 3, 4, 5])
      (5, 4)
      >>> get_greatest_2([-1, -5, -3, -7, -4])
      (-1, -3)
      """
output:     if len(items) < 2:
          raise ValueError("The list must contain at least two elements.")
      
      first_max = max(items)
      items.remove(first_max)
      second_max = max(items)
      
      return (first_max, second_max)