title: Call, Apply & Bind still gives 'undefined' for 'this' keyword
body: <p>Please see the code below:</p>
  
  <pre><code>let xy = {name:"matt", age: 44};
  let greetFunc = nickName =&gt; "Hello " + nickName + ". Your age is " + this.age + " now";
  console.log(greetFunc.call(xy, "vms"));
  </code></pre>
  
  <p>The result is:</p>
  
  <pre><code>Hello vms. Your age is undefined now
  </code></pre>
  
  <p>Why is 'this.age' returning 'undefined'? Any help would be appreciated. Thanks.</p>