You can define new exceptions of your own that are specific to your programs.
User-defined exceptions are coded with classes, which inherit from a built-in exception class: usually the class named Exception:
class AlreadyGotOne(Exception): pass # User-defined exception # from w ww . ja v a2s . co m def grail(): raise AlreadyGotOne() # Raise an instance try: grail() except AlreadyGotOne: # Catch class name print('got exception')