diff --git a/src/task_1/index.ts b/src/task_1/index.ts
index 53a04d7..2aa4549 100644
--- a/src/task_1/index.ts
+++ b/src/task_1/index.ts
@@ -26,3 +26,24 @@ class Calculator {
         return (this.a + this.b).toString();
     }
 }
+
+class BaseDecorator extends Calculator {
+    protected wrappee: Calculator;
+
+    constructor(a: number, b: number) {
+        super(a, b);
+        this.wrappee = new Calculator(a, b);
+    }
+}
+
+class DecorateRu extends BaseDecorator{
+    public exec(): string {
+        return `результат сложения ${this.a} + ${this.b} = ${this.wrappee.exec()}`;
+    }
+}
+
+class DecorateEn extends BaseDecorator{
+    public exec(): string {
+        return `result of the addition operation ${this.a} + ${this.b} = ${this.wrappee.exec()}`;
+    }
+}
\ No newline at end of file
diff --git a/src/task_2/index.ts b/src/task_2/index.ts
index 06535aa..6628713 100644
--- a/src/task_2/index.ts
+++ b/src/task_2/index.ts
@@ -12,3 +12,21 @@ class Example {
 let exampleInstance = new Example();
 exampleInstance.email = "fkkldfjg"; // генерирует эксепшен
 exampleInstance.email = "misha@mail.ru"; // выводит в консоль e-mail valid
+
+function validateMail(target: Object, propertyKey: string | symbol): any {
+    let email = ""
+    let descriptor: PropertyDescriptor = {
+        get() {
+            return email
+        },
+        set(newEmail: string) {
+            if (newEmail !== "" && !/[a-zA-Z0-9]+@[a-zA-Z0-9]+.[a-zA-Z0-9]+/.test(newEmail)) {
+                throw 'Invalid email.'
+            }
+            console.log('email valid');
+            email = newEmail;
+        }
+    }
+
+    return descriptor;
+}
diff --git a/src/task_4/index.ts b/src/task_4/index.ts
index dc0e179..f750ef8 100644
--- a/src/task_4/index.ts
+++ b/src/task_4/index.ts
@@ -6,6 +6,6 @@ function getProperty<T, K extends keyof T>(obj: T, key: K): T[K] {
     return obj[key];
 }
 
-const x = undefined;
+const x = {'m': 14};
 
 console.log(getProperty(x, "m")); 
\ No newline at end of file