sequence = ["beijing", "shanghai","beijing", "chongqing", "hubei",? ? ? ? ? ? "guangzhou", "guangzhou", "shanghai", "beijing"]def get_count(sequence):? ? i = {}? ? for x in sequence:? ? ? ? if x in i:? ? ? ? ? ? i[x] += 1? ? ? ? else:? ? ? ? ? ? i[x] = 1? ? return icounts = get_count(sequence)print counts? ? ? ? ? ? ? ?請問這串代碼中，具體是怎樣的運行順序啊，i這個字典是什么時候生成的？x最初不是應該也是一個列表么，為什么x in i后就生成了字典了啊，沒有理解這個