code: def getkth(self, k):
          "starts from 0"
          if k >= len(self):
              raise IndexError
          k += 1  # self has index -1
          h = len(self.next) - 1
          x = self
          while k:
              while x.next[h] is None or x.count[h] > k:
                  h -= 1
              k -= x.count[h]
              x = x.next[h]
          return x.kef getkth(self, k):
          "starts from 0"
          if k >= len(self):
              raise IndexError
          k += 1  # self has index -1
          h = len(self.next) - 1
          x = self
          while k:
              while x.next[h] is None or x.count[h] > k:
                  h -= 1
              k -= x.count[h]
              x = x.next[h]
          return x.key
docs: starts from 0