A smart aleck has provided you the following class: using PageCollection-std: :vector; class Book public: using iterator PageCollection: :iterator; using const_iterator PageCollection::const_iterator; private: std::string title; Author author; PageCollection pages; public: // title and author accessors I1 // title and author mutators Assume that PageCollection, Page, and Author are defined elsewhere. What functions must be added to Book to allow Book:iterator and Book::const_iterator to be used outside the Book class? A smart aleck has provided you the following class: using PageCollection-std: :vector; class Book public: using iterator PageCollection: :iterator; using const_iterator PageCollection::const_iterator; private: std::string title; Author author; PageCollection pages; public: // title and author accessors I1 // title and author mutators Assume that PageCollection, Page, and Author are defined elsewhere. What functions must be added to Book to allow Book:iterator and Book::const_iterator to be used outside the Book class