new_contents: class Solution(object):
      def findLUSlength(self, a, b):
          """
          :type a: str
          :type b: str
          :rtype: int
          """
          if a == b:
              return -1
          else:
              return max(len(a), len(b))
  
  
subject: Add py solution for 521. Longest Uncommon Subsequence I