What is proper way to require a method to be overridden?

[Robert Kern]

jeremito wrote:
> I am writing a class that is intended to be subclassed.  What is the
> proper way to indicate that a sub class must override a method?

raise NotImplementedError

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco