Python problem with upgrade from 19.10 to 20.04

[Chris Green]

I have recently upgraded my desktop system from ubuntu 19.10 to ubuntu
20.04.  I have some Oki printer/scanner driver software that is
written in Python 2 and, although python 2 is still installed on my
system it's no longer the default python and the Oki software no
longer runs.

The error I am getting is:-

    chris at esprimo$ ./scantool.py
    Traceback (most recent call last):
      File "./scantool.py", line 52, in <module>
        import gtk
    ImportError: No module named gtk

So what do I need to install on my Ubuntu 20.04 system to provide the
gtk module?

Alternatively (but much harder work) what is the Python 3 equivalent
of the the Python 2 pygtk and gtk modules.

-- 
Chris Green