The following DataNodes have no identifier: 3
http://classic.wikipathways.org/instance/WP3937_r120792 http://rdf.wikipathways.org/Pathway/WP3937_r120792/DataNode/a8fda (IgG)
http://classic.wikipathways.org/instance/WP3937_r120792 http://rdf.wikipathways.org/Pathway/WP3937_r120792/DataNode/a6dc7 (Pik3)
http://classic.wikipathways.org/instance/WP3937_r120792 http://rdf.wikipathways.org/Pathway/WP3937_r120792/DataNode/bef2c (TREM3)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier