Get the following after in Debian unstable "apt install cambalache".
$ cambalache Traceback (most recent call last): File "/usr/bin/cambalache", line 42, in <module> from cambalache.app import CmbApplication File "/usr/lib/python3/dist-packages/cambalache/__init__.py", line 90, in <module> from .cmb_view import CmbView File "/usr/lib/python3/dist-packages/cambalache/cmb_view.py", line 35, in <module> gi.require_version('Casilda', '0.1') ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^ File "/usr/lib/python3/dist-packages/gi/__init__.py", line 122, in require_version raise ValueError('Namespace %s not available' % namespace) ValueError: Namespace Casilda not available