The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP4190_r124024 http://rdf.wikipathways.org/Pathway/WP4190_r124024/DataNode/c8400 (protein prenylation)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier