( instructions: { 0: Read(( source: File("testfiles/rails.png"), format: Png, )), 1: Filter(Invert), 2: Write(( target: File("testfiles/gen/inverted.png"), format: Png, )), }, edges: { (on: 0, idx: 0): [(on: 1, idx: 0)], (on: 1, idx: 0): [(on: 2, idx: 0)], }, )