如何重复我的代码，但下次从变量中删除一个？

Question

I am making a python code as if I was going to put it in a car parking ticket machine. It goes through all the functions - displays the number of available parking spaces, asks for the last three digits of your registration plate, gets you to insert money but I am unsure how to take 1 away from the amount of available spaces for when I repeat the code. Also how do I repeat the code in doing so? Here is my code:

#Import
import time

#Variables:
spaces=100
ticketprice=3
cashin=0
totalcash=0
engineer='egg'

while True:


    #Beginning:
    print("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~")
    print("Harry's Car Park") 
    print("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~")
    print("There are currently", spaces,"spaces available")
    reg=input("Please enter the last three digits of your registration plate > ")


    #Engineer Mode
    if reg==engineer:
        print()
        print("YOU ARE NOW IN ENGINEER MODE")
        print()
        ticketprice=input("What would you like to change the ticket price to? ")
        print("Thank you! The ticket price has been changed to £", ticketprice)
        print()
        print("YOU ARE NO LONGER IN ENGINEER MODE")
        print()


    #Paying:
    print("Please insert £"+(str(ticketprice)+" to pay for your ticket:"))

    while totalcash<int(ticketprice):
        cashin=int(input("Enter pound coins here £"))
        totalcash=totalcash+cashin

        print()

        print("Thank you")

        print("Amount entered=£",totalcash)


    #Tickets
    if totalcash>int(ticketprice):
        print("Your change is £",totalcash-int(ticketprice))
        print()
        print("You have paid the full amount!")
        print()
        print("Printing Parking Ticket...")
        print()
        time.sleep(1)
        print("     ****************************************************")
        time.sleep(0.5)
        print("     *                        Harry's Car Park                      ")
        time.sleep(0.5)
        print("     *                                                                          ")
        time.sleep(0.5)
        print("     *                        Ticket Price: £",(int(ticketprice)),"                   ")
        time.sleep(0.5)
        print("     * 16/01/2020     Reg Plate:",(reg),"        17:03   ")
        time.sleep(0.5)
        print("     ****************************************************")

        print()


    if totalcash==int(ticketprice):
        print("You have paid the full amount!")
        print()
        print("Printing Parking Ticket...")
        print()
        time.sleep(1)
        print("     ****************************************************")
        time.sleep(0.5)
        print("     *                        Harry's Car Park                      ")
        time.sleep(0.5)
        print("     *                                                                          ")
        time.sleep(0.5)
        print("     *                        Ticket Price: £",(int(ticketprice)),"                      ")
        time.sleep(0.5)
        print("     * 16/01/2020     Reg Plate:",(reg),"        17:03      ")
        time.sleep(0.5)
        print("     ****************************************************")

        print()

Answer 1

What if only into IF final block (when you print ticket) you use spaces--; to reduce spaces? Also you should initialize it so it stores the maximum amount of spaces available

Answer 2

每当客户支付票款时，只需写空格-=1，然后添加一个条件，如果空格==0，则退出