remove duplicates from sorted array ii

class (object):
    def removeDuplicates(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        
        if len(nums) <= 2:
            return len(nums)
        cur = 2
        tail = 2
        while cur <= tail and tail < len(nums):
            nums[cur] = nums[tail]
            if nums[cur] == nums[cur-1] and nums[cur] == nums[cur-2]:
                # copy tail over then tail += 1
                tail += 1
            else:
                cur += 1
                tail += 1
        return cur