test
node1
BFO:0000001
entity
node2
BFO:0000003
occurrent
node1->node2
node2->node2
node6
BFO:0000015
process
node2->node6
node3
GO:0009987
cellular process
node4
GO:0033059
cellular pigmentation
node3->node4
node5
GO:0043473
pigmentation
node5->node4
node7
GO:0008150
biological_process
node6->node7
node7->node3
node7->node5