title: Function to get stored callback
body: <p>Suppose I have a variable, that stores the callback.</p>
  
  <pre><code>void* (*function)(int, double);
  </code></pre>
  
  <p>Now I would like to create a function, that will return this callback. I do not want the user to access the callback directly but by a function. This doesn't work:</p>
  
  <pre><code>void* (*)(int, double) getCallback();
  </code></pre>
  
  <p>My question is: What will the prototype for such function look like?</p>