[Twisted-Python] errorhandler example in docs needs work

[Tommi Virtanen]

Alan Ezust wrote:

>Reading this in the manual:
>    http://twistedmatrix.com/documents/current/howto/defer
>
>Example of how to write error handlers for exceptions:
>
>def errorHandler(failure):
>    failure.trap(SpamException, EggException)
>    # Handle SpamExceptions and EggExceptions
>
>d.addCallback(cookSpamAndEggs)
>d.addErrback(errorHandler)
>
>This example is missing something. The #handle SpamExceptions
>should have at least one statement after the # like
>      print "I am handling the exception"
>
>I look at this example above and I still don't know how to write an
>error handler. I shall read further, but I wanted to share my
>feedback.
>  
>
How would the print statement help you to know how to write an error 
handler?

Maybe there should be a "bigger" example somewhere, outside the defer howto,
with real code. Something like "try to fetch this URL via HTTP, retry up 
to three times".