As per tagged nans, check for JavaScript tagged NaN optimization. Essentially, the tag of the NaN (i.e. the mantissa) is interpreted as a pointer. Obviously, this is a very advanced use case, probably not worth Python guaranteeing such behavior.
Here is one article:

On Sat, Sep 12, 2020, 8:10 PM David Mertz <> wrote:
On Sat, Sep 12, 2020, 2:02 PM Steven D'Aprano <> wrote:
In general though, Python doesn't support generating the full range of NANs with payloads directly.

I've researched this a little bit for discussion in a book I'm writing, and I have not been able to identify ANY widely used programming language or tool that does anything meaningful with the NaN payloads.

It's possible I've missed something, but certainly not the top 20 languages are libraries that might come to mind.
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