Vertex: call:fmt.printf(str(hello: %s), var(s))
Vertex: str(greeting)
Vertex: str(hello: %s)
Vertex: str(world)
Vertex: var(s)
Edge: str(hello: %s) -> call:fmt.printf(str(hello: %s), var(s)) # a
Edge: str(world) -> var(s) # s
Edge: var(s) -> call:fmt.printf(str(hello: %s), var(s)) # b