計算機のプログラミングの中のresultという変数が上手く機能しません

僕はpython 3で簡単な計算が出来て10個までの計算結果をリストに保存出来てかつ10個目以降の答えをまた最初から保存できるプログラミングを作ったのですが何度プログラミングを組みなおしても

name 'result' is not defined

とresultの変数が定義されていないというエラーしか出ませんでした。「どこかresultを定義し忘れたかな?」と思いコードを何度か確認しましたが特に定義のし忘れやモジュールの中に変数のミスは見当たりませんでした。
このコードの中でresultの変数を定義をし忘れている個所あるいは変数のミスを教えてください

    answerlist = [0,0,0,0,0,0,0,0,0,0]
    counter = 1

    def decideprocess():
        global decision
        decision = str(input("Enter + for adding, - for subtracting, * for multiply, / for deviding, and 'all' for see what all calculation results so far. :"))

    def processes(result):
        global decision
        global counter
        decision = decideprocess()
        while decision == "+" or decision == "-" or decision == "*" or decision == "/" or decision == "all":
            if decision == "+":
                result = addition()
                decideprocess()

                return counter

            elif decision == "-":
                result = subtraction()
                decideprocess()

                return counter

            elif decision == "*":
                result = multiplecation()
                decideprocess()

                return counter

            elif decision == "/":
                result = devision()
                decideprocess()

                return counter

            elif decision == "all":
                for a in range(0,len(answerlist)):
                    print(answerlist[a])
                decideprocess()

            else :
                showallresult()

        return result

    def addition():
        global counter
        a = float(input("Enter any number. :"))
        b = float(input("Enter any number. :"))
        result = a + b
        print(result)
        counter = counter + 1
        assignment(result)

        return(result)

    def subtraction():
        global counter
        a = float(input("Enter any number. :"))
        b = float(input("Enter any number. :"))
        result = a - b
        print(result)
        counter = counter + 1
        assignment(result)


        return result

    def multiplecation():
        global counter
        a = float(input("Enter any number. :"))
        b = float(input("Enter any number. :"))
        result = a * b
        print(result)
        counter = counter + 1
        assignment(result)


        return result

    def devision():
        global counter
        a = float(input("Enter any number. :"))
        b = float(input("Enter any number. :"))
        result = a / b
        print(result)
        counter = counter + 1
        assignment(result)


        return result

    def assignment(result):
        global counter
        while counter < 10:
            assignmentanswer(result)
        if counter >= 10:
            changecountervalue()
            assignmentanswerover10(result ,newcounter)

        return result, newcounter

    def assignmentanswer(result):
        global counter
        answerlist[counter] = result

        return result

    def changecountervalue():
        global counter
        counter10 = int(counter/10)
        newcounter = (counter10*10) - counter

        return newcounter

    def assignmentanswerover10(result, newcounter):
        answerlist[newcounter] = result

        return result, newcounter

    def showallresult():
        for a in range(0,len(answerlist)):
            print(answerlist[a])

    def calculator(result):
        global counter
        global decision
        processes(result)

        return result

    def CALCULATOR(result):
        calculator(result)

        return result



CALCULATOR(result)