I think making 'Ellipsis' a reserved word is too much. The analogy with non-reserved words like `int`, `str`, `map`, `print`, and so on, illustrate this, I think. I.e. redefining those is likely to cause bad things to happen, but we're consenting adults, and in the end they are just names.
However, I think improving the repr() of the Ellipsis object itself to remind users of the connection with its special literal `...` is a great idea.
Originally, the notation "..." could only be used inside a subscript,
and anywhere else, you'd have to spell it "Ellipsis". Now that you can
use "..." anywhere, would it be worth switching the repr to just be
that?
ChrisA
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