title: Default implementation of method in interface
body: <p>Is there any way to make default implementation of method in interface? I cannot make it in a baseclass unfortunately. I feel this is pretty easy question, but cannot find the right solution for a quite long moment.</p>
  
  <p>/edit In my example I need something like this:</p>
  
  <pre><code>class A {
    somePropertyA;
    someFunctionA() {
      console.log(this.somePropertyA);
    }
  }
  class B {
    somePropertyB;
    someFunctionB() {
      console.log(this.somePropertyB);
    }
  }
  class C {
    // Here we want to have someFunctionA() and someFunctionB()
    // without duplicating code of this implementation.
  }
  </code></pre>
  
  <p>The solution of B entends A and C extends B is for me a not so optimal.</p>