new_contents: #!/usr/bin/env python
  
  import roslib
  import rospy # for writing a ROS node
  import sys
  from dynamixel_msgs.msg import JointState
  from std_msgs.msg import Float64
  import math
  
  
  # def state_callback(motor):
  	# print motor.current_pos
  
  def commander():
  	pub = rospy.Publisher('/jnt_controller/command', Float64)
  	rospy.init_node('commander', anonymous=True)
  	r = rospy.Rate(10)
  
  	dt = 0
  
  	while not rospy.is_shutdown():
  		pub.publish(math.sin(dt))
  		dt += 0.05
  
  		r.sleep()
  
  # Main
  if __name__ == '__main__':
  
  
  	# subscribe to the /motor_states/arm_port topic, which publishes
  	# messages of type MotorStateList, and receive data from that topic in
  	# the callback function state_callback
  	# rospy.Subscriber("/jnt_controller/state", JointState, state_callback)
  	commander()
  
  
  
  	# keep node from exiting until node is stopped
  	# rospy.spin()
  
subject: add sin_test program