[[!comment format=mdwn
 username="joey"
 subject="""comment 1"""
 date="2016-02-24T21:09:52Z"
 content="""
`checkResult` is the key to understanding this. Its (simplified) type
signature:

	checkResult :: m a -> (a -> m Result) -> p i -> Property i

It's being given getstat as the first parameter. It runs that before the
property does anything, and it passes that value to comparestat.

So, oldstat is the getstat value from before the property did anything.
"""]]
