assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:4438  oio:id           DOID:4438  xsd:string  
1          0           graph  DOID:7867  rdfs:subClassOf  DOID:4438  _IRI        
1          0           graph  DOID:8078  rdfs:subClassOf  DOID:4438  _IRI