Implemented 2D visualization for notes using Vue Flow

node_modules/d3-selection/src/matcher.js

@@ -0,0 +1,12 @@
+export default function(selector) {
+  return function() {
+    return this.matches(selector);
+  };
+}
+
+export function childMatcher(selector) {
+  return function(node) {
+    return node.matches(selector);
+  };
+}
+