setting argument for teleop twist keyboard in launch file

edit

Hi, I am learning gmapping, rviz and map_server. I created launch file which will launch stage_ros, teleop_twist_keyboard, gmapping with purpose creating a map as below:

<launch>
    <node pkg="stage_ros" type="stageros" name="stage" args="$(find stage_ros)/world/willow-erratic.world"/>
    <node pkg="gmapping" type="slam_gmapping" name="gmapping">
        <param name="scan" value="base_scan"/>
    </node>
    <node pkg="teleop_twist_keyboard" type="teleop_twist_keyboard.py" name="teleop"/>
    <node pkg="rviz" type="rviz" name="rviz" args="$find stage_ros)/rviz/stage.rviz"/>
</launch>

But when I ran this launch file, I got this error

... 
setting /run_id to c042b11c-fc87-11e5-b686-00044b581868
process[rosout-1]: started with pid [4026]
started core service [/rosout]
process[stage-2]: started with pid [4029]
process[gmapping-3]: started with pid [4035]
process[teleop-4]: started with pid [4042]
process[rviz-5]: started with pid [4048]
[rviz-5] process has died [pid 4048, exit code -7, cmd /opt/ros/indigo/lib/rviz/rviz $find stage_ros)/rviz/stage.rviz __name:=rviz __log:=/home/ubuntu/.ros/log/c042b11c-fc87-11e5-b686-00044b581868/rviz-5.log].
log file: /home/ubuntu/.ros/log/c042b11c-fc87-11e5-b686-00044b581868/rviz-5*.log
/opt/ros/indigo/lib/teleop_twist_keyboard/teleop_twist_keyboard.py:61: SyntaxWarning: The publisher should be created with an explicit keyword argument 'queue_size'. Please see http://wiki.ros.org/rospy/Overview/Publishers%20and%20Subscribers for more information.
  pub = rospy.Publisher('cmd_vel', Twist)

I am not sure how to fix this. Please help me.

Thank you.