title: i want to extend from one class but delete some property
body: <p>I have some class for crud API service class
  I want to extend it but spear few properties
  for exam this is my class</p>
  <pre><code>class Parent {
    public propertyToKeep: any;
    public propertyToDelete: any;
    constructor() { }
  }
  </code></pre>
  <p>this is the child class</p>
  <pre><code>class Child extends Parent {
    constructor() {
      super();
    }
  }
  </code></pre>
  <p>Another file
  where I don't want to see and get access to</p>
  <pre><code>export class comeComponent {
    constructor(private child: Child) {
      this.child.propertyToKeep // work
      this.child.propertyToDelete // error and I can't even see it
    }
  }
  </code></pre>