test
node1
BFO:0000003
occurrent
node1->node1
node2
BFO:0000015
process
node1->node2
node6
GO:0008150
biological_process
node2->node6
node3
GO:0008152
metabolic process
node4
GO:0071704
organic substance
metabolic process
node3->node4
node5
BFO:0000001
entity
node5->node1
node6->node3