Returns a filter which will exclude nodes that match a set of filters.

Returns a filter which will include nodes that match a set of filters.

Returns an operational state node filter if state is true.

Filter configuration nodes.

Filter configuration and operational state nodes.

Filter opd: extension nodes.

Filter operational state nodes, which are config false.

TODO: We should make this able to be configured.

* To add extensions to the schema tree a simple pattern is followed.

FeaturesChecker checks the status of a feature feature is formatted <module>:<feature name>.