function rosn() {
        if [ "$1" = "" ]; then
            topic=$(rosnode list | percol | xargs -n 1 rosnode info | percol | sed -e 's%.* \* \(/[/a-zA-Z0-9_]*\) .*%\1%')
        else
            topic=$(rosnode info $1 | percol | sed -e 's%.* \* \(/[/a-zA-Z0-9_]*\) .*%\1%')
        fi
        if [ "$topic" != "" ] ; then
            rost $topic
        fi
    }
    function rost() {
        if [ "$1" = "" ]; then
            node=$(rostopic list | percol | xargs -n 1 rostopic info | percol | sed -e 's%.* \* \(/[/a-zA-Z0-9_]*\) .*%\1%')
        else
            node=$(rostopic info $1 | percol | sed -e 's%.* \* \(/[/a-zA-Z0-9_]*\) .*%\1%')
        fi
        if [ "$node" != "" ] ; then
            rosn $node
        fi
    }