class BagOfThings {
///it will have following methods

	//This method will add one object to the collection.
	// It should have constant time complexity
	??? add(Object o)


	//This method will will remove given object from the collection.
	// It should have constant time complexity
	??? remove(Object o)
	
	// This method should return num of random objects. The objects from the collection should be picked randomly. They should never be in any order.
	// Multiple calling of this method with same value of num, will return different collection each time.
	??? getNoOfThings(int num)
}