code: def _installed_fonts(cls):
          
          fonts = {}
          for d in cls._font_directories():
              for key, path in cls._iter_font_files_in(d):
                  fonts[key] = path
          return fonts
docs: Return a dict mapping a font descriptor to its font file path,
          containing all the font files resident on the current machine. The
          font descriptor is a (family_name, is_bold, is_italic) 3-tuple.