Fix MethodAmbiguity errors #191

Job	Run time
test (1.6, ubuntu-latest, x64, Others)	1m 50s
test (1.6, ubuntu-latest, x64, ForwardDiff)	1h 42m 21s
test (1.6, ubuntu-latest, x64, Tracker)	15m 8s
test (1.6, ubuntu-latest, x64, ReverseDiff)	56m 9s
test (1.6, ubuntu-latest, x64, Zygote)	32m 2s
test (1, ubuntu-latest, x64, Others)	2m 6s
test (1, ubuntu-latest, x64, ForwardDiff)	53m 53s
test (1, ubuntu-latest, x64, Tracker)	11m 25s
test (1, ubuntu-latest, x64, ReverseDiff)	13m 37s
test (1, ubuntu-latest, x64, Zygote)	23m 44s
test (1, macOS-latest, x64, Others)	4m 5s
test (1, macOS-latest, x64, ForwardDiff)	1h 45m 0s
test (1, macOS-latest, x64, Tracker)	11m 52s
test (1, macOS-latest, x64, ReverseDiff)	14m 29s
test (1, macOS-latest, x64, Zygote)	41m 5s
	8h 8m 46s

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