assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:2237  oio:id           DOID:2237  xsd:string  
1          0           graph  DOID:1884  rdfs:subClassOf  DOID:2237  _IRI        
1          0           graph  DOID:2044  rdfs:subClassOf  DOID:2237  _IRI