An American asset-or-nothing call option (with parameters K, F and expiration time t) can be exercised any time up to t. If the securitys price when the option is exercised is K or higher, then the amount F is returned; if the securitys price when the option is exer- cised is less than K, then nothing is returned. Explain how you can use the multiperiod binomial model to approximate the risk-neutral price of an American asset-or-nothing call option.