input: def third_largest(lst: list) -> int:
      """
      Get the third largest element in a given row.
      
      >>> third_largest([12, 13, 13, 45, 22, 99])
      22
      >>> third_largest([100, 200, 300, 400, 500])
      300
      """
output:     if len(lst) < 3:
          return None
      lst = sorted(set(lst), reverse=True)
      return lst[2] if len(lst) >= 3 else None