code: def set_size(self, pt=None, px=None):
          
  
          assert (pt, px) != (None, None)
  
          if pt is not None:
              self.__init__(pt, self.font_name)
          else:
              self.__init__(self.px_to_pt(px), self.font_name)
docs: Set the size of the font, in px or pt.
  
          The px method is a bit inacurate, there can be one or two px less, and max 4 for big numbers (like 503)
          but the size is never over-estimated. It makes almost the good value.