title: How does `isInstanceOf` work?
body: <p>Assume, we have:</p>
  
  <pre><code>class B
  class A extends B
  trait T
  </code></pre>
  
  <p>Then it holds:</p>
  
  <pre><code>val a: A with T = new A with T 
  a.isInstanceOf[B]  // result is true !
  </code></pre>
  
  <p>Is it right to say, the <code>isInstanceOf</code> method checks, if there is at least one type (not all types) which matches the right hand side in a subtype relationship? </p>
  
  <p>At first look, I thought a value with type <code>A with T</code> can not be a subtype of <code>B</code>, because <code>A</code> <strong>and</strong> <code>T</code> are not both subtypes of <code>B</code>. But it is <code>A</code> <strong>or</strong> <code>T</code> is a subtype of <code>B</code> -- is that right ?</p>