input: def third_largest(lst):
      """ Get the third largest element from a given list, considering only distinct elements.
      >>> third_largest([12, 13, 13, 45, 22, 99])
      22
      """
output:     lst = list(set(lst))
      if len(lst) < 3:
          return None
      lst.sort(reverse=True)
      return lst[2]