Python [PEP-585](https://peps.python.org/pep-0585/) replaces a number of
`typing` module types with built-in equivalents and `collections.abc`
versions as of Python 3.9, with the aim of eventually removing the
`typing` module versions of these classes altogether. Since the minimum
required version of Python listed in the [Contribution Tools
document](https://github.com/carbon-language/carbon-lang/blob/trunk/docs/project/contribution_tools.md#main-tools)
is 3.9, the type hints in the various python files in the repo can be
updated to this style of type hint without a need for backwards
compatibility.
Feel free to close if this isn't a desired change at this time!
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Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
My intent is to add CARBON_ bas a prefix, and this makes that easier by creating a tool for auto-fixing guards in general.
string_literal is a manual fix -- it had no guard and I didn't automate that (technically I think I could, especially by enforcing the file header/footer, but it didn't feel quite worth it to me).
Jack McCluskeyandJon Ross-Perkins