[RFC]: Add functions `guess_parse` and `guess_alphabet` #726

Job	Run time
test (1.5, x86, ubuntu-latest, false)	1m 37s
test (1.5, x86, windows-latest, false)	11m 25s
test (1.5, x86, macOS-latest, false)	3m 15s
test (1, x86, ubuntu-latest, false)	1m 38s
test (1, x86, windows-latest, false)	2m 21s
test (1, x86, macOS-latest, false)	2m 10s
test (nightly, x86, ubuntu-latest, true)	2m 34s
	25m 0s

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