How to set the param into the argument in launch file ?

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Can I first set the param in Python and then set the param into the argument in launchfile???

first I set the param in python, rospy.set_param('robot_global_name',robot_global_name)

then I load the param in launchfile, <rosparam ns="robotsss" command="dump" param="robot_global_name" />

the question is how can I send the param into the argument, or how can I use the param as an argument, that i can launch the specific robot?

Another parallel qustion, Can man use the python to send the variable into launchfile as an argument ?

I have used this way,

 sys.argv=['roslaunch', 'launch_files', 'all_in.launch', 'robot_global_name:='+robot_global_name]
import roslaunch
roslaunch.main()

but it also used the roslaunch, but I just want to use the argument 'robot_global_name:='+robot_global_name