NameError name Solution is not defined ret Solution singleNumber param 1 Line 30 in driver Solution py driver Line 41 in module Solution py

Question

def singleNumber(self, nums: List[int]) -> int:
        nums_dict = [nums]
        
        for x in nums:
          count = nums_dict[x]
          nums_dict[x] = nums_dict[x]+1
        
        for x in nums:
          count = nums_dict[x]
          if count is not None and count == 1:
                return x