Make a type private #31

Job	Run time
tests / cargo-test-debug (ubuntu-24.04)	2m 46s
tests / cargo-test-debug (macos-latest)	2m 51s
tests / cargo-test-debug (windows-2022)	4m 12s
tests / cargo test (linux, release)	2m 25s
build / build (ubuntu-24.04-arm, aarch64-unknown-linux-musl, -e JEMALLOC_SYS_WITH_LG_PAGE=16, musllinux_1...	7m 55s
build / build (ubuntu-24.04, x86_64-unknown-linux-musl, musllinux_1_2, container, python:3.11-alpine, --p...	9m 28s
build / build (ubuntu-24.04, i686-unknown-linux-gnu, container, python:3.11-slim-trixie, --platform linux...	11m 13s
build / build (ubuntu-24.04, x64, x86_64-unknown-linux-gnu, native)	8m 46s
build / build (ubuntu-24.04-arm, arm64, aarch64-unknown-linux-gnu, native, -e JEMALLOC_SYS_WITH_LG_PAGE=16)	7m 19s
build / build (ubuntu-24.04-arm, armv7-unknown-linux-gnueabihf, container, python:3.11-slim-trixie, --pla...	7m 58s
build / build (ubuntu-24.04, i686-unknown-linux-musl, musllinux_1_2, container, python:3.11-alpine, --pla...	9m 3s
build / build (ubuntu-24.04-arm, armv7-unknown-linux-musleabihf, musllinux_1_2, container, python:3.11-al...	7m 32s
build / build (macos-15-intel, x64, x86_64, native)	10m 36s
build / build (windows-2022, x86, i686-pc-windows-msvc, native)	11m 51s
build / build (macos-latest, arm64, aarch64, native)	8m 8s
build / build (windows-2022, x64, x86_64-pc-windows-msvc, native)	12m 32s
publish	1m 15s
	2h 5m 50s

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