Particularly in value and literal patterns.
This is getting a little bit into the guards aspect of matching.
We could similarly add reverse flow in terms of
sub-patterns storing to a sequence pattern,
a flow step from alternatives to an-or-pattern, etc..
It does not seem too likely that sources are embedded in patterns
to begin with, but for secrets perhaps?
It is illustrated by the literal test. The value test still fails.
I believe we miss flow in general from the static attribute.
- also update `validTest.py`, but commented out for now
otherwise CI will fail until we force it to run with Python 3.10
- added debug utility for dataflow (`dataflowTestPaths.ql`)
