title: What is the FlexibleContexts extension good for? Could you please explain it using a simple example?
body: <p>I was trying to understand what the FlexibleContexts extension is doing by searching for web pages that would explain it to mere mortals (people who have read LYHFGG, for example, like me) but I did not find any such resource.</p>
  
  <p><strong>Therefore</strong> I ask the experts on the topic: Could you please explain what this extension does, why it exists, and give one or two simple examples how and why one should use it?</p>
  
  <p><strong>Furthermore</strong>, If I am reading someone else's code <a href="https://github.com/ryantrinkle/reflex/blob/develop/test/Reflex/Test/CrossImpl.hs" rel="noreferrer">which</a> uses this extension, then what should I know about the extension in order to understand the code written using this extension?</p>