elif命令==“退出”：^ IndentationError：unindent与任何外部缩进级别都不匹配

Question

    command = ""
  while True:
      command = input(">").lower()
  if command == "start":
    print("Car started...")
  elif command == "stop":
    print("car stopped...")
  elif command == "help":
    print("""
start - to start the car    
stop - to stop the car
quit - to quit
    """)
  elif command == "quit":
    break
  else:
     print("I don't understand...")