Failure w/ ubuntu 18

[caleb15]

sound-output-switcher(master): ./sound-output-switcher
Traceback (most recent call last):
  File "./sound-output-switcher", line 19, in <module>
    import gobject
ImportError: No module named gobject

[caleb15]

I followed the gobject installation directions here:

https://pygobject.readthedocs.io/en/latest/getting_started.html#ubuntu-getting-started

but it says everything was already installed:

sound-output-switcher(master): sudo apt install python3-gi python3-gi-cairo gir1.2-gtk-3.0
[sudo] password for caleb:
Reading package lists... Done
Building dependency tree       
Reading state information... Done
gir1.2-gtk-3.0 is already the newest version (3.22.30-1ubuntu4).
python3-gi is already the newest version (3.26.1-2ubuntu1).
python3-gi-cairo is already the newest version (3.26.1-2ubuntu1).