title: Call functions from within a wxPython event handler
body: <p>I'm struggling to find a way to use function from within a wxPython event handler function.  Say I have a button that when clicked it runs a function called OnRun using an event handler.  However, the user forgot to click a RadionButton before the OnRun button and I want to pop-up a MessageDialog telling them they forgot a step.  I'm going to reuse this MessageDialog several times, thus rather than doing a copy/paste of the same code I would like to just have this MessageDialog in a function and call this MessageDialog function if the user forgets to check a RadioButton.  </p>
  
  <p>If this wasn't a function used in an Event Handler I know I could simply put the function as an argument but I'm not seeing a way I can do this with these.  Any help here would be appreciated.  </p>