class account {.
  public:
    account(const char* ="none", float=0);
    virtual void statement();
  private:
    ...
};
class checking : public account {.
  ...
protected:
    void statement();
};
class student : public checking {.
  ...
  protected:
    void statement();
};
 app:    student smith("Kyle smith", 5000, "UT");
       account* pa = &smith;
       pa->statement();  //okay.