def hello_world():
    print('Hello, world!')
hello_world()

def add_numbers(a, b):
    return a + b
print(add_numbers(5, 3))

def reverse_list(lst):
    return lst[::-1]
print(reverse_list([1, 2, 3, 4, 5]))

import threading
def print_numbers():
    for i in range(10):
        print(i)
thread = threading.Thread(target=print_numbers)
thread.start()

class Person:
    def __init__(self, name):
        self.name = name
    def say_hello(self):
        print('Hello, my name is ' + self.name)
person = Person('Alice')
person.say_hello()

def factorial(n):
    if n == 0:
        return 1
    else:
        return n * factorial(n - 1)
print(factorial(5))