Write a Flask Web API with only 1 method called ProcessPayment that receives a request like this - CreditCardNumber (mandatory, string, it should be a valid credit card number) - CardHolder: (mandatory, string) - ExpirationDate (mandatory, DateTime, it cannot be in the past) - SecurityCode (optional, string, 3 digits) - Amount (mandatoy decimal, positive amount)

The response of this method should be 1 of the followings based on -

Payment is processed: 200 OK

The request is invalid: 400 bad request

Any error: 500 internal server error

The payment could be processed using different payment providers (external services) called: - PremiumPaymentGateway - ExpensivePaymentGateway - CheapPaymentGateway. The payment gateway that should be used to process each payment follows the next set of business rules: a) If the amount to be paid is less than 20, use CheapPaymentGateway. b) If the amount to be paid is 21-500, use ExpensivePaymentGateway if available. Otherwise, retry only once with CheapPaymentGateway. c) If the amount is > 500, try only PremiumPaymentGateway and retry up to 3 times in case payment does not get processed.