code: def makeFontBoundingBox(self):
          
          if not hasattr(self, "glyphBoundingBoxes"):
              self.glyphBoundingBoxes = self.makeGlyphsBoundingBoxes()
          fontBox = None
          for glyphName, glyphBox in self.glyphBoundingBoxes.items():
              if glyphBox is None:
                  continue
              if fontBox is None:
                  fontBox = glyphBox
              else:
                  fontBox = unionRect(fontBox, glyphBox)
          if fontBox is None:  # unlikely
              fontBox = BoundingBox(0, 0, 0, 0)
          return fontBox
docs: Make a bounding box for the font.
  
          **This should not be called externally.** Subclasses
          may override this method to handle the bounds creation
          in a different way if desired.