#includeIn this example, we create three SlotVisitor objects and append visitor2 and visitor3 to visitor1's visitor list using the append function. We then call the visitAllSlots function on visitor1 which visits all the slots of all the visitors in the visitor list. The SlotVisitor class is likely part of a larger package library that is used for implementing the Visitor design pattern in C++.#include "SlotVisitor.h" int main() { SlotVisitor visitor1("Visitor 1"); SlotVisitor visitor2("Visitor 2"); SlotVisitor visitor3("Visitor 3"); visitor1.append(&visitor2); visitor1.append(&visitor3); visitor1.visitAllSlots(); return 0; }