Getting sample-xml-skeleton plugin needs a valid module, when i am trying to convert yang file to XML using command pyang -f sample-xml-skeleton -o router.xml router.yang

[mitshett]

I am trying to convert a yang file to XML using command -> pyang -f sample-xml-skeleton -o router.xml router.yang

getting below error sample-xml-skeleton plugin needs a valid module when i try to run the above command