text: #!/usr/bin/env python
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  ## Simple talker demo that published std_msgs/Strings messages
  ## to the 'chatter' topic
  
  import rospy
  from std_msgs.msg import String
  
  pub = None
  # publish a message to subscribers when we die
  def talker_shutdown():
      print("I'm dead!")
      pub.publish("I'm dead!")
      
  def talker():
      global pub
      pub = rospy.Publisher('chatter', String)
      rospy.init_node('talker', anonymous=True)
  
      # register talker_shutdown() to be called when rospy exits
      rospy.on_shutdown(talker_shutdown)
      
      import time
      time.sleep(2.0)
  
      rospy.signal_shutdown('test done')
          
  if __name__ == '__main__':
      talker()
  