new_contents: class Solution:
      # @param A a list of integers
      # @return an integer
      def removeDuplicates(self, A):
          if not A:
              return 0
          if len(A) == 1:
              return 1
          j = 0  # Position of last processed non-duplicate
          n = len(A)
          twice = False  # Whether last processed non-duplicate appreared twice
          for i in range(1, n):
              # Duplicate is found
              if A[i] == A[j] and not twice:
                  twice = True
                  j += 1
                  A[j] = A[i]
              elif A[i] != A[j]:
                  j += 1
                  A[j] = A[i]
                  twice = False
          return j + 1
  
subject: Remove Duplicates from Sorted Array II