c++ design pattern for template method

write demo code to describe this pattern,you can wrap some step that must do,but someone of step is not make sure,that should confirmed by subclass in running time.

/*************************************************************************
    > File Name: template_method.cc
  > Author: perrynzhou
  > Mail: [email protected]
  > Created Time: Tue 15 Aug 2017 07:11:20 AM EDT
 ************************************************************************/

#include 
using namespace std;
class IDocument {
public:
    IDocument() { cout << "IDocument" << endl; }
    void run()
    {
        step0();
        step1();
        step2();
        step3();
    }

private:
    virtual void step3() = 0;
    void step0() { cout << "...call step0..." << endl; }
    void step1() { cout << "...call step1..." << endl; }
    void step2() { cout << "...call step2..." << endl; }
};
class MyDocument : public IDocument {
public:
    MyDocument() { cout << "MyDocument" << endl; }
private:
    void step3() { cout << "...call MyDocument.step3..." << endl; }
};
int main(void)
{
    MyDocument md;
    md.run();
    return 0;
}