How to use "__new__"?

[Terry Reedy]

"could ildg" <could.net at gmail.com> wrote in message 
news:311b5ce105032917276a188c59 at mail.gmail.com...
> __new__() is intended mainly to allow subclasses of immutable types
> (like int, str, or tuple) to customize instance creation.

Exactly.  It is an anwer to the conundrum: How do you give an immutable 
object its unchangeable value.  It is much like how to move an unmovable 
object to its permanent position ;-).

TJR