Test.ConfigSourcetype t = {seed : Seed.t;seed is used to initialize the pseudo-random state before running tests of a property.
test_count : Base.int;test_count determines how many random values to test a property with.
shrink_count : Base.int;shrink_count determines the maximum number of attempts to find a smaller version of a value that fails a test.
sizes : Base.int Base.Sequence.t;sizes determines the progression of value sizes to generate while testing. Testing fails if sizes is not of length at least test_count.
}