We were inconsistent on this one. I consider it particularly useful when
a method starts with a `return` statement.
In other cases, we probably shouldn't have a guard rule in the middle of
a method in any case, but that's a different refactoring.
Some specs where breaking close to midnight because 30.years.ago uses zone.now and Time.now.utc.to_date doesn't.
Also this will make all codebase consistent in the way time is deal with
