fix: improve type checking and documentation across multiple files #28

Job	Run time
Build psutil wheels on ubuntu-latest	17s
Build psutil wheels on ubuntu-latest	14s
Build psutil wheels on windows-latest	39s
Build psutil wheels on windows-latest	1m 21s
Build psutil wheels on macos-latest	35s
Build psutil wheels on macos-latest	15s
Build psutil wheels on macos-latest	13s
Build psutil wheels on windows-latest	46s
Build psutil wheels on ubuntu-latest	10s
release	7s
	4m 37s

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