### 1. **Using `self`**

**Assignment:**

Create a class `Student` with attributes `name` and `marks`. Use the `self` keyword to initialize these values via a constructor. Add a method `display()` that prints student details.

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### 2. **Using `cls`**

**Assignment:**

Create a class `Counter` that keeps track of how many objects have been created. Use a class variable and a class method with `cls` to manage and display the count.

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### 3. **Public Variables and Methods**

**Assignment:**

Create a class `Car` with a public variable `brand` and a public method `start()`. Instantiate the class and access both from outside the class.

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### 4. **Class Variables and Class Methods**

**Assignment:**

Create a class `Bank` with a class variable `bank_name`. Add a class method `change_bank_name(cls, name)` that allows changing the bank name. Show that it affects all instances.

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### 5. **Static Variables and Static Methods**

**Assignment:**

Create a class `MathUtils` with a static method `add(a, b)` that returns the sum. No class or instance variables should be used.

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### 6. **Constructors and Destructors**

**Assignment:**

Create a class `Logger` that prints a message when an object is created (constructor) and another message when it is destroyed (destructor).

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### 7. **Access Modifiers: Public, Private, and Protected**

**Assignment:**

Create a class `Employee` with:

- a public variable `name`,

- a protected variable `_salary`, and

- a private variable `__ssn`.

Try accessing all three variables from an object of the class and document what happens.

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### 8. **The `super()` Function**

**Assignment:**

Create a class `Person` with a constructor that sets the name. Inherit a class `Teacher` from it, add a subject field, and use `super()` to call the base class constructor.

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### 9. **Abstract Classes and Methods**

**Assignment:**

Use the `abc` module to create an abstract class `Shape` with an abstract method `area()`. Inherit a class `Rectangle` that implements `area()`.

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### 10. **Instance Methods**

**Assignment:**

Create a class `Dog` with instance variables `name` and `breed`. Add an instance method `bark()` that prints a message including the dog's name.

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### 11. **Class Methods**

**Assignment:**

Create a class `Book` with a class variable `total_books`. Add a class method `increment_book_count()` to increase the count when a new book is added.

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### 12. **Static Methods**

**Assignment:**

Create a class `TemperatureConverter` with a static method `celsius_to_fahrenheit(c)` that returns the Fahrenheit value.

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### 13. **Composition**

**Assignment:**

Create a class `Engine` and a class `Car`. Use composition by passing an `Engine` object to the `Car` class during initialization. Access a method of the `Engine` class via the `Car` class.

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### 14. **Aggregation**

**Assignment:**

Create a class `Department` and a class `Employee`. Use aggregation by having a `Department` object store a reference to an `Employee` object that exists independently of it.

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### 15. **Method Resolution Order (MRO) and Diamond Inheritance**

**Assignment:**

Create four classes:

- `A` with a method `show()`,

- `B` and `C` that inherit from `A` and override `show()`,

- `D` that inherits from both `B` and `C`.

Create an object of `D` and call `show()` to observe MRO.

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### 16. **Function Decorators**

**Assignment:**

Write a decorator function `log_function_call` that prints "Function is being called" before a function executes. Apply it to a function `say_hello()`.

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### 17. **Class Decorators**

**Assignment:**

Create a class decorator `add_greeting` that modifies a class to add a `greet()` method returning "Hello from Decorator!". Apply it to a class `Person`.

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### 18. **Property Decorators: `@property`, `@setter`, and `@deleter`**

**Assignment:**

Create a class `Product` with a private attribute `_price`. Use `@property` to get the price, `@price.setter` to update it, and `@price.deleter` to delete it.

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### 19. **`callable()` and `__call__()`**

**Assignment:**

Create a class `Multiplier` with an `__init__()` to set a factor. Define a `__call__()` method that multiplies an input by the factor. Test it with `callable()` and by calling the object like a function.

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### 20. **Creating a Custom Exception**

**Assignment:**

Create a custom exception `InvalidAgeError`. Write a function `check_age(age)` that raises this exception if `age < 18`. Handle it with `try...except`.

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### 21. **Make a Custom Class Iterable**

**Assignment:**

Create a class `Countdown` that takes a start number. Implement `__iter__()` and `__next__()` to make the object iterable in a for-loop, counting down to 0.