title: How to get parameters of factory functions
body: <p>Assuming I've got the code in Python 3.5</p>
  
  <pre class="lang-py prettyprint-override"><code>def factory(param):
      def f(num):
          print(param*num)
      return f
  
  fun = factory('a')
  # how do I know, that fun was created with param='a'?
  fun(3)
  </code></pre>
  
  <p>How can I inspect <code>param</code> value after <code>fun</code> was created?</p>