Some users can be confused by syntax error message for assigning to ellipsis [1]:

>>> ... = 1
  File "<stdin>", line 1
    ... = 1
    ^^^
SyntaxError: cannot assign to Ellipsis here. Maybe you meant '==' instead of '='?

because Ellipsis is a name of a builtin variable Ellipsis, and it is possible to assign to variable named Ellipsis.

>>> Ellipsis = 1
>>> Ellipsis
1

I think that using lowercase spelling of "ellipsis" will eliminate confusion.

[1] https://mail.python.org/archives/list/python-ideas@python.org/thread/KDQ3OHALLXVZJIGPC4BMPVS2XH3VFPJV/