AirplaneQueue, toy class by Bill Arndt command to run tests: rspec spec A software subsystem of an air-traffic control system is defined to manage a queue of aircraft (AC) in an airport. The aircraft queue is managed by a process which responds to three types of requests: - system boot used to start the system. - enqueue aircraft used to insert a new AC into the system. - dequeue aircraft used to remove an AC from the system. AC’s have the following properties: AC type: Passenger or Cargo AC size: Small or Large The process which manages the queue of AC’s satisfies the following: There is no limit on the number of AC’s it can manage (could be tens of thousands) Dequeue aircraft requests result in selection of one AC for removal such that: Passenger AC’s have removal precedence over Cargo AC’s Large AC’s of a given type have removal precedence over Small AC’s of the same type. Earlier enqueued AC’s of a given type and size have precedence over later enqueued AC’s of the same type and size.