Implemented 2D visualization for notes using Vue Flow

node_modules/d3-selection/src/selection/exit.js

@@ -0,0 +1,6 @@
+import sparse from "./sparse.js";
+import {Selection} from "./index.js";
+
+export default function() {
+  return new Selection(this._exit || this._groups.map(sparse), this._parents);
+}