code: def add_drawing(self, drawing_id=None, dump=True, **kwargs):
          
          if drawing_id not in self._drawings:
              drawing = Drawing(self, drawing_id=drawing_id, **kwargs)
              self._drawings[drawing.id] = drawing
              self.controller.notification.emit("drawing.created", drawing.__json__())
              if dump:
                  self.dump()
              return drawing
          return self._drawings[drawing_id]
docs: Create an drawing or return an existing drawing
  
          :param dump: Dump the topology to disk
          :param kwargs: See the documentation of drawing