That’s not a type. A NaN is a floating point number (of type float). I used numpy because that’s the easiest way to get a NaN.

This is part of the floating point standard.

This was never about None, which is a completely different thing.

NaN is a special floating point value. https://en.wikipedia.org/wiki/IEEE_754

It’s weird but it makes sense why it was chosen to be this way.

They say a picture is worth a thousand words.

It’s not true in a normal programming language. If it is true in yours, you should stop using it immediately.