diff --git a/Observable.js b/Observable.js
index 03545cd..909d85d 100644
--- a/Observable.js
+++ b/Observable.js
@@ -11,12 +11,16 @@ class ObserverList {
   }
   add(observer) {
     // todo add observer to list
+    this.observerList.push(observer);
   }
   remove(observer) {
     // todo remove observer from list
+    const idx = this.observerList.indexOf(observer);
+    this.observerList.splice(idx, 1);
   }
   count() {
     // return observer list size
+    return this.observerList.length;
   }
 }
 
@@ -26,12 +30,17 @@ class Subject {
   }
   addObserver(observer) {
     // todo add observer
+    this.observers.add(observer)
   }
   removeObserver(observer) {
     // todo remove observer
+    this.observers.remove(observer)
   }
   notify(...args) {
     // todo notify
+    for(let i = 0; i < this.observers.count(); i++) {
+      this.observers.observerList[i].update(...args)
+    }
   }
 }
 
diff --git a/PubSub.js b/PubSub.js
index 0c7999e..156f82c 100644
--- a/PubSub.js
+++ b/PubSub.js
@@ -13,14 +13,31 @@ module.exports = class PubSub {
 
   subscribe(type, fn) {
     // todo subscribe
+    let sub = this.subscribers[type]
+    if (sub) {
+      sub.push(fn);
+    } else {
+      this.subscribers[type] = [fn];
+    }
   }
 
   unsubscribe(type, fn) {
     // todo unsubscribe
+    if (!this.subscribers[type]) return;
+    const sub = this.subscribers[type];
+    const idx = sub.indexOf(fn);
+    if (idx >= 0) {
+      sub.splice(idx, 1);
+    }
   }
 
   publish(type, ...args) {
     // todo publish
+    const sub = this.subscribers[type];
+    if (!sub) return;
+    sub.forEach(fn => {
+      fn(...args);
+    })
   }
 
 }