func simplePatch() -> Patch {

    let generator = Node(name: "generator", outputs: ["out"])
    let processor = Node(name: "processor", inputs: ["in"], outputs: ["out"])
    let mixer = Node(name: "mixer", inputs: ["in1", "in2"], outputs: ["out"])
    let output = Node(name: "output", inputs: ["in"])

    let nodes = [generator, processor, generator, processor, mixer, output]

    let wires = Set([Wire(from: OutputID(0, 0), to: InputID(1, 0)),
                     Wire(from: OutputID(1, 0), to: InputID(4, 0)),
                     Wire(from: OutputID(2, 0), to: InputID(3, 0)),
                     Wire(from: OutputID(3, 0), to: InputID(4, 1)),
                     Wire(from: OutputID(4, 0), to: InputID(5, 0))])

    var patch = Patch(nodes: nodes, wires: wires)
    patch.recursiveLayout(nodeIndex: 5, point: CGPoint(x: 800, y: 50))
    return patch
}

struct ContentView: View {
    @State var patch = simplePatch()
    @State var selection = Set<NodeIndex>()

    var body: some View {
        NodeEditor(patch: $patch, selection: $selection)
    }
}