test
node1
BFO:0000003
occurrent
node1->node1
node6
BFO:0000015
process
node1->node6
node2
GO:0008219
cell death
node3
GO:0012501
programmed cell death
node2->node3
node4
GO:0008150
biological_process
node5
GO:0009987
cellular process
node4->node5
node5->node2
node6->node4
node7
BFO:0000001
entity
node7->node1