[Python-ideas] Optional parameters without default value

[Serhiy Storchaka]

On 02.03.17 12:04, M.-A. Lemburg wrote:
> This is not new syntax, nor is it a keyword. It's only a
> new singleton and it is well usable outside of function
> declarations as well, e.g. for class attributes which are
> not yet initialized (and which can accept None as value).

If it is not a keyword, it could be used in expressions, e.g. assigned 
to a variable or passed to a function. It could be monkey-patched or 
hidden by accident (as True and False in Python 2).