<launch>

  <arg name="required" />
  <arg name="if_test" />
  <arg name="include_arg" />  
  
  <arg name="optional" default="not_set" />
  <arg name="grounded" value="set" />

  <arg name="param1_name" value="p1" />
  <arg name="param2_name" value="p2" />
  <arg name="param3_name" value="p3" />
  <arg name="param4_name" value="p4" />
  
  <arg name="param1_value" value="$(arg required)" />
  <arg name="param2_value" value="$(arg optional)" />
  <arg name="param3_value" value="$(arg grounded)" />

  <group ns="include_test">
    <param name="$(arg param1_name)_test" value="$(arg param1_value)" />
    <param name="$(arg param2_name)_test" value="$(arg param2_value)" />
    <param name="$(arg param3_name)_test" value="$(arg param3_value)" />
    <param name="$(arg param4_name)_test" value="$(arg include_arg)" />
  </group>

</launch>
