title: Python __call__ special method practical example
body: <p>I know that <code>__call__</code> method in a class is triggered when the instance of a class is called. However, I have no idea when I can use this special method, because one can simply create a new method and perform the same operation done in <code>__call__</code> method and instead of calling the instance, you can call the method.</p>
  
  <p>I would really appreciate it if someone gives me a practical usage of this special method.</p>