Improve data model & fix tests

backend/src/Model/spec/Tree.spec.ts

@@ -1,6 +1,6 @@
-import { Edge, Tree, TreeNode, TreeNodeFactory } from '../'
-import { expect } from 'chai';
-import 'mocha';
+import { Tree, TreeNodeFactory } from '../'
+import { expect } from 'chai'
+import 'mocha'
 
 import './TreeNode.findNode'
 
@@ -10,7 +10,7 @@ describe('Tree', () => {
 
     const topics = 'foo/bar'.split('/')
     const leaf = TreeNodeFactory.fromEdgesAndValue(topics, 3)
-    debugger
+
     tree.updateWithNode(leaf.firstNode())
     let expectedNode = tree.findNode('foo/bar')
     expect(expectedNode).to.eq(leaf)