C$-2\mathrm{.}28$ The PredatoryCreditCard class of Section $2\mathrm{.}4\mathrm{.}1$ provides a process$\_$month method that models the completion of a monthly cycle. Modify the class so that once a customer has made ten calls to charge in the current month, each additional call to that function results in an additional $$1$ surcharge.

C$-2\mathrm{.}29$ Modify the PredatoryCreditCard class from Section $2\mathrm{.}4\mathrm{.}1$ so that a customer is assigned a minimum monthly payment, as a percentage of the balance, and so that a late fee is assessed if the customer does not subsequently pay that minimum amount before the next monthly cycle.

C$-2\mathrm{.}30$ At the close of Section $2\mathrm{.}4\mathrm{.}1,$ we suggest a model in which the CreditCard class supports a nonpublic method, $\_$set$\_$balance$($b$),$ that could be used by subclasses to affect a change to the balance, without directly accessing the $\_$balance data member. Implement such a model, revising both the CreditCard and PredatoryCreditCard classes accordingly.