Summary: I went looking for a CPAN graph module so I could merge multiple
directed graphs. I found two that looked good, by famous Perl authors.
Unfortunately both have issues.
1. Graph::Easy looks good, but it has not changed in years and has a bug
list
For a specific one-off specific task like this, I would assume that
would take more work to find and evaluate a module that solves my
problem than it would take to roll my own solution.
Heck, in this case you can arrange it as a map-reduce. Your initial
map takes each file, and spits out
