帮我写一段ros控制机械臂移动的python代码

# 定义机械臂变量
import rospy
from std_msgs.msg import Stringarm = rospy.Publisher('/arm_controller', String, queue_size=10)# 开始移动机械臂
def move_arm():
rate = rospy.Rate(10) # 10hz
while not rospy.is_shutdown():
arm_cmd = 'move arm'
rospy.loginfo(arm_cmd)
arm.publish(arm_cmd)
rate.sleep()# 主函数，初始化节点
if __name__ == '__main__':
try:
rospy.init_node('arm_mover', anonymous=True)
move_arm()
except rospy.ROSInterruptException:
pass