public static Op quadizeBlock(Op op) { final Deque<QuadSlot> stack = new ArrayDeque<>() ; QuadSlot qSlot = new QuadSlot(Quad.defaultGraphNodeGenerated, Quad.defaultGraphNodeGenerated) ; stack.push(qSlot) ; // Starting condition OpVisitor before = new Pusher(stack) ; OpVisitor after = new Popper(stack) ; TransformQuadBlockGraph qg = new TransformQuadBlockGraph(stack, before, after) ; return Transformer.transformSkipService(qg, null, op, before, after) ; }