While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
* Extract Percentile-type functions from Statistics (e.g. PERCENTILE(), PERCENTRANK(), QUARTILE(), and RANK())
* Unit test for PERCENTILE() with an empty (of numbers) dataset
Adrien Crivelli
Mark Baker