code: def project_point(cb, msg, attributes=('x', 'y')):
      
      if skip(cb, msg, attributes): return msg
      plot = get_cb_plot(cb)
      x, y = msg.get('x', 0), msg.get('y', 0)
      crs = plot.current_frame.crs
      coordinates = crs.transform_points(plot.projection, np.array([x]), np.array([y]))
      msg['x'], msg['y'] = coordinates[0, :2]
      return {k: v for k, v in msg.items() if k in attributes}
docs: Projects a single point supplied by a callback