ماشین حساب ساده با پایتون

total = 0
while True:
    user_answer = str(input('if you want to end calc enter end: '))
    if user_answer.lower() == 'end':
        print('***')
        print()
        print('Total Calculation Amount: {}'.format(total))
        print()
        print('***')   
        break
    else:
        user_input_number = int(input('please enter the number: '))
        while True:
            print('''
            + : addition
            - : subtraction
            / : division
            * : multiply
            ''')
            user_input_symbol = str(input('please enter the symbol (+*-/) : '))
            if user_input_symbol == '*':
                total = total * user_input_number
                break
            elif user_input_symbol == '/':
                total = total / user_input_number
                break
            elif user_input_symbol == '+':
                total = total + user_input_number
                break
            elif user_input_symbol == '-':
                total = total - user_input_number
                break
            else:
                print('You have entered the wrong symbol, TRY AGAIN!')