public void ChangeState(IPlaneObjectState newState)
 {
     if (this.currentlyRunningState != null)
     {
         this.currentlyRunningState.Exit();
     }
     this.previousState         = this.currentlyRunningState;
     this.currentlyRunningState = newState;
     this.currentlyRunningState.Enter();
 }
 public void SwitchToPreviousState()
 {
     this.currentlyRunningState.Exit();
     this.currentlyRunningState = this.previousState;
     this.currentlyRunningState.Enter();
 }