Reference implementation for PEP 828 #2343

Job	Run time
x86_64-unknown-linux-gnu/gcc-free-threading	7m 43s
aarch64-apple-darwin/clang	9m 41s
aarch64-unknown-linux-gnu/gcc	7m 4s
x86_64-pc-windows-msvc/msvc-free-threading	4m 41s
x86_64-apple-darwin/clang	17m 53s
x86_64-unknown-linux-gnu/gcc	9m 19s
x86_64-pc-windows-msvc/msvc	9m 53s
	1h 6m 14s

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