new_contents: from itertools import groupby
  class Solution(object):
      def isPossible(self, nums):
          """
          :type nums: List[int]
          :rtype: bool
          """
          prev = None
          not_full_1, not_full_2, attach = 0, 0, 0
          for n, items in groupby(nums):
              cnt = len(list(items))
              if prev is None:
                  not_full_1 = cnt
              elif prev + 1 == n:
                  if not_full_1 + not_full_2 > cnt:
                      return False
                  else:
                      cnt -= not_full_1 + not_full_2
                  attach = min(attach, cnt)
                  cnt -= attach
                  not_full_1, not_full_2, attach = cnt, not_full_1, not_full_2 + attach
              else:
                  if not_full_1 + not_full_2 > 0:
                      return False
                  not_full_1, not_full_2, attach = cnt, 0, 0
              prev = n
          return not_full_1 + not_full_2 == 0
  
subject: Add py solution for 659. Split Array into Consecutive Subsequences