title: Jasmine: callThrough and callFake
body: <p>I have just started investigating in Jasmine, and currently, I am having trouble understanding the call through, return value, and call fake spies.</p>
  <p>I read the official documentation, but it doesn't make much sense to me. In addition, I tried to search for an answer on StackOverflow or Google, but couldn't find a sufficient explanation.</p>
  <p>Could anyone please explain it in a more dummy-friendly way? :)</p>