code: def main():
      watcher = WatcherBase()
      console_pub = Stream(stream_name="S1", console_debug=True)
      stream = watcher.create_stream(expr="lambda vars:vars.x**2")
      console_pub.subscribe(stream)
  
      for i in range(5):
          watcher.observe(x=i)
  
label_desc: Use image node_id 1 for calling a global function with example usage: main() without return types