diff --git a/src/app/store/initiable.ts b/src/app/store/initiable.ts
new file mode 100644
index 0000000..f938e57
--- /dev/null
+++ b/src/app/store/initiable.ts
@@ -0,0 +1,6 @@
+export abstract class Initiable {
+  protected constructor() {
+    this.initiate();
+  }
+  protected abstract initiate();
+}
diff --git a/src/app/store/inner-node.ts b/src/app/store/inner-node.ts
index 655ca69..6f37af8 100644
--- a/src/app/store/inner-node.ts
+++ b/src/app/store/inner-node.ts
@@ -1,11 +1,9 @@
 import { Node } from './node';
-import { observableToBeFn } from 'rxjs/internal/testing/TestScheduler';
 
 export abstract class InnerNode extends Node {
-  parent: Node;
-  nextVersion: this = null;
-
-  protected readonly children: Array<InnerNode> = [];
+  readonly children: Array<InnerNode> = [];
+  protected parent: Node;
+  private nextVersion: this = null;
 
   get latestVersion(): this {
     let version;
@@ -15,16 +13,6 @@ export abstract class InnerNode extends Node {
     return version;
   }
 
-  protected constructor(parent: Node) {
-    super();
-
-    new Promise(r => r()).then(() =>
-      parent.addChild({
-        value: this
-      })
-    );
-  }
-
   mutatedUpdate() {
     this.parent.mutatedUpdate();
   }
@@ -33,30 +21,20 @@ export abstract class InnerNode extends Node {
     return this.update((self: this) => this.cloneWithMap.call(self, map));
   }
 
-  changeKey({ propertyName, value }: { propertyName: string; value: any }): this {
-    return this.update((self: this) => this.cloneWithAdd.call(self, { propertyName, value }));
-  }
-
   changeKeys(props: { [propertyName: string]: any }): this {
     return this.update((self: this) => this.cloneWithChangedKeys.call(self, props));
   }
 
-  changeValue({ oldValue, newValue }: { oldValue: any; newValue: any }): this {
-    return this.update((self: this) => this.cloneWithModify.call(self, { oldValue, newValue }));
-  }
-
-  addChild(update: { value: InnerNode }) {
+  addChild(update: { child: InnerNode }) {
     super.addChild.call(this.latestVersion, update);
   }
 
   changeChild(update: { oldValue: InnerNode; newValue: InnerNode }) {
-    super.changeChild.call(this.latestVersion, update);
+    super.replaceChild.call(this.latestVersion, update);
   }
 
   protected abstract cloneWithMap(map: (a: this) => void): this;
-  protected abstract cloneWithAdd(update: { value: any; propertyName: string }): this;
   protected abstract cloneWithChangedKeys(props: { [propertyName: string]: any }): this;
-  protected abstract cloneWithModify(update: { oldValue: any; newValue: any }): this;
 
   private update(cloneMethod: (self: this) => this): this {
     if (this.nextVersion !== null) {
@@ -72,7 +50,7 @@ export abstract class InnerNode extends Node {
       child.parent = clone;
     }
 
-    this.parent.changeChild({
+    this.parent.replaceChild({
       oldValue: this,
       newValue: clone
     });
diff --git a/src/app/store/node.ts b/src/app/store/node.ts
index c9d1384..1bee7cd 100644
--- a/src/app/store/node.ts
+++ b/src/app/store/node.ts
@@ -1,36 +1,32 @@
 import { InnerNode } from './inner-node';
+import { Unique } from './unique';
 
-export abstract class Node {
-  protected static id = 0;
-  protected static sumCopyCount = 0;
-  protected abstract readonly children: Array<InnerNode>;
-  private id = Node.id++;
-  protected copyCount = 1;
-
-  abstract changeKey(update: { propertyName: string; value: any });
-  abstract changeValue(update: { oldValue: any; newValue: any });
-
-  constructor() {
-    Node.sumCopyCount++;
-  }
-
+export abstract class Node extends Unique {
+  readonly children: Array<InnerNode>;
+  // TODO: fix types.
+  protected abstract changeKeys(props: any): this;
   abstract mutatedUpdate(): void;
 
-  addChild(update: { value: InnerNode }) {
-    this.changeValue({
-      oldValue: this.children,
-      newValue: [...this.children, update.value]
+  private copyCount = 0;
+
+  protected initiate() {
+    super.initiate();
+    this.copyCount++;
+  }
+
+  addChild({ child }: { child: InnerNode }) {
+    this.changeKeys({
+      children: [...this.children, child]
     });
   }
 
-  changeChild({ oldValue, newValue }: { oldValue: InnerNode; newValue: InnerNode }) {
+  replaceChild({ oldValue, newValue }: { oldValue: InnerNode; newValue: InnerNode }) {
     if (oldValue === newValue) {
       return;
     }
 
-    this.changeValue({
-      oldValue: this.children,
-      newValue: this.children.map(c => (c === oldValue ? newValue : c))
+    this.changeKeys({
+      children: this.children.map(c => (c === oldValue ? newValue : c))
     });
   }
 
@@ -45,6 +41,6 @@ export abstract class Node {
 
   public log() {
     console.log(this._log());
-    console.log(`All in all, there are ${Node.sumCopyCount} objects.`);
+    console.log(`All in all, there are ${Unique.ObjectCount} objects.`);
   }
 }
diff --git a/src/app/store/unique.ts b/src/app/store/unique.ts
new file mode 100644
index 0000000..a8228e4
--- /dev/null
+++ b/src/app/store/unique.ts
@@ -0,0 +1,17 @@
+import { Initiable } from './initiable';
+
+export abstract class Unique extends Initiable {
+  protected static nextId = 0;
+  static get ObjectCount(): number {
+    return Unique.nextId;
+  }
+
+  get id(): number {
+    return this._id;
+  }
+  private _id: number;
+
+  protected initiate() {
+    this._id = Unique.nextId++;
+  }
+}