new_contents: from collections import Counter
  class Solution(object):
      def findLHS(self, nums):
          """
          :type nums: List[int]
          :rtype: int
          """
          c = Counter(nums)
          m = 0
          for k in c:
              if k + 1 in c:
                  m = max(m, c[k] + c[k + 1])
          return m
  
subject: Add py solution for 594. Longest Harmonious Subsequence