#include <iostream>
class Base {
public:
    static Base *staticMember;
 
    static void baseMethod();
};
 
Base * Base::staticMember;
 
class Derived : public Base {
public:
    void derivedMethod();
};
 
void Base::baseMethod() {
    if ( staticMember )
        std::cout << "not null";
    else
        std::cout << "null";
}
 
void Derived::derivedMethod() {
    staticMember = new Derived();
}
 
int main() {
    Derived* derived = new Derived();
    derived->derivedMethod();
    Base::baseMethod();
}

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