✅ ✅ Use function that has default implementation in interface from instance of class

interface IFoo
{
  void DoThing1();
  void DoThing2();

  void DoMultipleThings(int thing1, int thing2)
  {
    for (int i = 0; i < thing1; i++)
    {
      this.DoThing1();
      for (int j = 0; j < thing2; j++)
      {
        this.DoThing2();
      }
    }
  }
}

class Bar : IFoo
{
  void DoThing1() => //something
  void DoThing2() => //something
}

Bar bar = new Bar();
bar.DoMultipleThings(5, 5);