title: Dynamic return Type based on string
body: <p>Is it possible to pass a string to a function and assign a dynamic type that is returned? </p>
  
  <pre><code>class MyService {
    aMethod(arg) {
      console.log(arg)
    }
  }
  
  Container.register('my_service', MyService);
  
  // Internally Container holds a Object 
  export interface IServiceInstance {
      name: string;
      type: Function;
      instance: Object;
  }
  
  const myServiceInstance = Container.get('my_service')
  
  // myServiceInstance should be detected as type of MyService class
  myServiceInstance.aMethod('Hello World') 
  
  // Currently I use it like this. But if it is possible I want to get rid of that
  const myServiceInstance = (Container.get('my_service') as MyService)
  </code></pre>