$ grep -F 'GNU General Public License version 3' -R . ./plainbox/impl/signal.py:# it under the terms of the GNU General Public License version 3,
Everything else is GPL-3+
$ grep -F 'GNU General Public License version 3' -R . impl/signal. py:# it under the terms of the GNU General Public License version 3,
./plainbox/
Everything else is GPL-3+