assertion  retraction  graph  subject     predicate        object     datatype    annotation
1          0           graph  DOID:2921   oio:id           DOID:2921  xsd:string  
1          0           graph  DOID:2986   rdfs:subClassOf  DOID:2921  _IRI        
1          0           graph  DOID:14064  rdfs:subClassOf  DOID:2921  _IRI