Finding the point in the parsing where the rule kicks in.
The thread pool is already gone. You can't schedule any work on it any more.
Mind your destructors.
Different usage on this side of the pond.
Just a lot of hot air.
All null pens are functionally equivalent, so why have more than one? Are some pens more null than others?
If you ever have to debug one of these things.
If you are the one calling the delegate, you have an extra thing to worry about.
Fiddling a knob that isn't connected to anything.
How failures in the wild get categorized by analysis.