/// <summary>
        /// Called when an avatar completes a station, this will remove that station's states
        /// </summary>
        public void RemoveStation(ModelStation station)
        {
            if (station is HoldingStation)
            {
                // Holding stations don't need to be removed
                return;
            }

            WalkToStationState thisStationWalkState = mWalkToStationStates[station];

            mAtStationStates.Remove(station);
            mWalkToStationStates.Remove(station);

            foreach (WalkToStationState walkState in mWalkToStationStates.Values)
            {
                walkState.RemoveTransition(thisStationWalkState);
            }

            mWalkToCenterState.RemoveTransition(thisStationWalkState);
            mWalkToEndGoalState.RemoveTransition(thisStationWalkState);
        }
        /// <summary>
        /// Constructs a FashionModelStateMachine for the given model. Model must have needs before creating the state machine (so that the proper states for each station can be created)
        /// </summary>
        public FashionModelStateMachine(FashionModel model, FashionLevel level)
        {
            if (model == null)
            {
                throw new ArgumentNullException("model");
            }
            mModel = model;

            mInactiveState = new ModelInactiveState(model);

            mWalkToEndGoalState = new WalkToEndGoal(model, level);
            mInactiveState.AddTransition(mWalkToEndGoalState);

            mWalkToEndGoalState.AddTransition(mInactiveState);

            mWalkToCenterState = new WalkToCenterState(model, level);
            mWalkToCenterState.AddTransition(mInactiveState);

            List <ModelStation> possibleStations = new List <ModelStation>(model.RequiredStations);

            foreach (HoldingStation station in level.HoldingStations)
            {
                possibleStations.Add(station);
            }
            foreach (ModelStation station in possibleStations)
            {
                WalkToStationState walkToStation = new WalkToStationState(model, station, level);

                AtStationState atStation = new AtStationState(model, station);
                atStation.AddTransition(mWalkToCenterState);
                atStation.AddTransition(mInactiveState);

                // All the WalkToStation states can enter the corresponding AtStation state
                walkToStation.AddTransition(atStation);
                walkToStation.AddTransition(mInactiveState);

                mAtStationStates.Add(station, atStation);

                // If the model doesn't need to stay at this station, it could go back to walk to center
                walkToStation.AddTransition(mWalkToCenterState);

                mWalkToEndGoalState.AddTransition(walkToStation);

                // An avatar walking to center can be redirected to a station
                mWalkToCenterState.AddTransition(walkToStation);

                mWalkToStationStates.Add(station, walkToStation);
            }

            // Make it so that avatars can be interrupted from walking to
            // one station by sending them to another station they need
            foreach (WalkToStationState stateA in mWalkToStationStates.Values)
            {
                foreach (WalkToStationState stateB in mWalkToStationStates.Values)
                {
                    stateA.AddTransition(stateB);
                }
            }

            mWalkToCenterState.AddTransition(mWalkToEndGoalState);

            mModel.Clickable = mInactiveState.Clickable;
            this.EnterInitialState(mInactiveState);
        }