assertion  retraction  graph  subject     predicate        object     datatype    annotation
1          0           graph  DOID:4072   oio:id           DOID:4072  xsd:string  
1          0           graph  DOID:1737   rdfs:subClassOf  DOID:4072  _IRI        
1          0           graph  DOID:10021  rdfs:subClassOf  DOID:4072  _IRI