code: def singleNumber(self, nums: List[int]) -> int:
      counter = Counter(nums)
  
      for item, value in counter.items():
          if value == 1:
              return item
  
      return 0
  
label_desc: Use image node_id 1 for calling the Solution obj's underlying member method code with example usage: obj.singleNumber(nums) and returns: int, item