public interface Human {
    void Eat();
    void Run();
}

public class Man : Human {
    public void Eat() {
        //eat code
    };

    public void Run() {
        //run code
    }
}

public class Baby : Human {
    public void Eat() {
        //eat code
    }

    //babies can not run so what??
    //NotImplementedException fired
}