diff --git a/Observable.js b/Observable.js
index 03545cd..3758743 100644
--- a/Observable.js
+++ b/Observable.js
@@ -10,13 +10,25 @@ class ObserverList {
     this.observerList = [];
   }
   add(observer) {
-    // todo add observer to list
+    return this.observerList.push(observer);// todo add observer to list
   }
   remove(observer) {
     // todo remove observer from list
+    for (let index = 0; index < this.observerList.length; index++) {
+      if(this.observerLis[index]==observer){
+        this.observerList.splice(index,1);
+      }
+      
+    }
   }
   count() {
     // return observer list size
+    return this.observerList.length;
+  }
+  get(index){
+    if (index<-1 && index<this.observerList.length) {
+       return this.ObserverList[index];
+    }
   }
 }
 
@@ -25,13 +37,21 @@ class Subject {
     this.observers = new ObserverList();
   }
   addObserver(observer) {
-    // todo add observer
+    this.observer.add(observer);// todo add observer
   }
   removeObserver(observer) {
     // todo remove observer
+    this.observer.remove(observer);
   }
   notify(...args) {
     // todo notify
+    var observerCont=this.observers.count();
+    // for (let index = 0; index < observerCont.length; index++) {
+    //   this.observers.get[i].update(args);
+    // }
+    this.observers.ObserverList.forEach(observe => {
+      observe.update(...args);
+    });
   }
 }
 
diff --git a/PubSub.js b/PubSub.js
index 0c7999e..0de117a 100644
--- a/PubSub.js
+++ b/PubSub.js
@@ -13,14 +13,25 @@ module.exports = class PubSub {
 
   subscribe(type, fn) {
     // todo subscribe
+    if (!this.subscribers[type]) {
+      this.subscribers[type]=[];
+    }
+    this.subscribers[type].push(fn);
   }
 
   unsubscribe(type, fn) {
+    if(this.subscribers[type]==fn){
+      delete this.subscribers[type]
+    }
     // todo unsubscribe
   }
 
   publish(type, ...args) {
     // todo publish
-  }
+       this.subscribers[type].forEach(fn => {
+         fn(...args);
+       });
+    }
+  
 
 }
diff --git a/package.json b/package.json
index a7933a0..1e857b3 100644
--- a/package.json
+++ b/package.json
@@ -18,5 +18,8 @@
   "homepage": "https://github.com/FE-star/exercise17#readme",
   "devDependencies": {
     "mocha": "^5.0.0"
+  },
+  "dependencies": {
+    "should": "^13.2.3"
   }
 }