through, the bottom part of the stack needs to be implemented via
grepping, and that turns our messages into API.
+ It seems there are at least two trees of abstractness (area, check
+ and message in question form one, category potentially another,
+ albeit perhaps degenerated) that we may want to filter
+ independently. E.g. I might want to filter out all
+ .debug_info/sev<1, or I might want to simply filter out sev<1 right
+ away.
+
* quirks
Some compilers produce files broken in various ways. Not to be