Enum with only a single member

[Paul Rubin]

Steven D'Aprano <steve+comp.lang.python at pearwood.info> writes:
> Is it silly to create an enumeration with only a single member?

No.  

> That is, a singleton enum?

Why stop there?  You can make empty ones too.  (Zerotons?)

> The reason I ask is that I have two functions that take an enum
> argument. 

Sounds like a good reason.

> def spam(arg):
>     if isinstance(arg, MarxBros): 
> def ham(arg):
>     if isinstance(arg, MarxBros) or arg is Unique.FOO:

> Good, bad or indifferent?

Ummmm, that's ugly, but the alternatives are worse unless there's more
branches, and maybe even then.