#include <iostream>
#include <memory>
using namespace std;
 
struct Interface {
    virtual void f () = 0;
    virtual ~Interface() {};
};
 
struct SomeClass {
    virtual void additionalBehaviour () = 0;
    void g () {
        additionalBehaviour ();
        /*Some stuff with printing into a ostringstream*/
    }
};
 
struct Derived : public SomeClass, public Interface {
    void additionalBehaviour () override { cout<<"additional"<<endl; /*Some printing to oss*/ }
    void f () override { g (); }
};
 
int main () {
    unique_ptr<Interface> ifc (new Derived ());
    ifc->f ();
    cout << "HI!" << endl;
    return 0;
}
 

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