*前言：這篇算是一個總結筆記

利用閉包返回一個計數器函式，每次呼叫它返回遞增整數：

• 建立生成器：

def createCounter():
    def f():
        x = 0
        while True:
            x += 1
            yield x
    it = f()

    def number():
        return next(it)
    return number

createA = createCounter()
print(createA())

• 列表

  def createCounter():
  	f = [0]
  	def increase():
  		f[0] = f[0] + 1
  		return f[0]
  	return increase
  
  createA = createCounter()
  print(createA())
  print(createA())
  print(createA())