text: #!/usr/bin/env python
  import rospy
  from std_msgs.msg import String
  
  rospy.init_node('talker')
  pub = rospy.Publisher('chatter', String, queue_size=10)
  rate = rospy.Rate(10)
  while not rospy.is_shutdown():
      hello_str = String()
      hello_str.data = "hello world %s" % rospy.get_time()
      # rospy.loginfo(hello_str.data)
      pub.publish(hello_str)
      rate.sleep()
  