code: public void remove(Robot robot) {
  	if (!robotsPosition.containsKey(robot)) {
  	    throw new IllegalArgumentException("Robot doesn't exist");
  	}
  
  	Point lastPosition = robotsPosition.get(robot);
  	robotsPosition.remove(robot);
  	delayer.removeListener(robot.getSerialNumber());
  	eventDispatcher.fireEvent(new RobotRemovedEvent(robot, lastPosition));
  
      }
docs: Removes a robot from the world and triggers a {@link RobotRemovedEvent}
  
  @param robot the robot to remove from the board