class Foo
{
  public:
    Foo() { value = 0; };
    Foo& operator<<(const Foo&) { value++;  return *this; };
    int value;
};

void doFoo()
{
    Foo f;
    f << Foo();
    f << Foo();
    //f.value == 2
}

//After "Extract Method" refactoring:
//MyMethod should either take a (Foo& f) or possibly return a Foo (if Foo supports the assignment operator)
void MyMethod(Foo f) 
{
    f << Foo();
}

void doFooAfterExtractMethod()
{
    Foo f;
    MyMethod(f);
    MyMethod(f);
    //f.value == 0
}