python - Detect missing glyphs in text

I have written a Python3 appindicator which calls fortune and captures the output for display in the on-screen notification.

Some fortunes contain squares with a hexadecimal number when the corresponding glyph does not exist in the current font. Each square is the representation of the hexadecimal Unicode code point for the missing glyph.

I want to remove the hexadecimal text before I display to the user. I was hoping to find some Python API which would let me inspect text, character by character, to determine something like char.isValidCodePoint() or similar but I cannot find as such.

I found a possible solution that I wanted to investigate here but after installing fonttools via the terminal, my Python program could not import fonttools/fontTools.

Any ideas - either using the Python API or calling out to a terminal?

Update #1: I have since realised the fonttools sample code from the link above will not work for me as it is Python2. I suppose if fonttools could somehow be used, I could invoke a Python2 interpreter from my Python3 script.

Update #2: After lots of reading (see references below), I have since found fc-match but it cannot always uniquely identify the font in use. I obtain the current font in Python:

from gi.repository import Gio
fontName = Gio.Settings( "org.gnome.desktop.interface" ).get_string( "font-name" )

resulting in Ubuntu 11. Passing this result to pango-view along with the hexadecimal character, I get a list of fonts including Ubuntu. To my thinking if the glyph was NOT rendered by the font, the font should not appear in the result from pango-view!

References: