Allow specification of initial state for `sample` #255

Job	Run time
test (1.6, ubuntu-latest, x86, 1)	3m 45s
test (1.6, ubuntu-latest, x64, 1)	3m 25s
test (1.6, macOS-latest, x64, 1)	1s
test (1.6, windows-latest, x64, 1)	3m 29s
test (1, ubuntu-latest, x86, 1)	2m 53s
test (1, ubuntu-latest, x86, 2)	3m 41s
test (1, ubuntu-latest, x64, 1)	3m 44s
test (1, ubuntu-latest, x64, 2)	3m 45s
test (1, macOS-latest, x64, 1)	1s
test (1, macOS-latest, x64, 2)	1s
test (1, windows-latest, x64, 1)	3m 19s
test (1, windows-latest, x64, 2)	2m 51s
test (nightly, ubuntu-latest, x86, 1)	1m 9s
test (nightly, ubuntu-latest, x86, 2)	1m 41s
test (nightly, ubuntu-latest, x64, 1)	1m 30s
test (nightly, ubuntu-latest, x64, 2)	1m 43s
test (nightly, macOS-latest, x64, 1)	1s
test (nightly, macOS-latest, x64, 2)	1s
test (nightly, windows-latest, x64, 1)	34s
test (nightly, windows-latest, x64, 2)	54s
	38m 28s

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