Add `provide` and `hidden` for symbol_assignments #121

Job	Run time
Check clippy	25s
Check format	11s
Run tests	31s
msrv	2m 46s
Publish	41s
release artifact for x86_64-pc-windows-gnu	1m 33s
release artifact for x86_64-pc-windows-msvc	1m 31s
release artifact for x86_64-apple-darwin	54s
release artifact for aarch64-apple-darwin	52s
release artifact for x86_64-unknown-linux-musl	39s
release artifact for x86_64-unknown-linux-gnu	45s
	10m 48s

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