def my_decorator(func):
    def wrapper():
        print("Something is happening before the function is called.")
        func()
        print("Something is happening after the function is called.")
    return wrapper
@my_decorator
def say_hello():
    print("Hello!")
say_hello()

def repeat(n):
    def decorator(func):
        def wrapper(*args, **kwargs):
            for _ in range(n):
                func(*args, **kwargs)
        return wrapper
    return decorator
@repeat(3)
def greet(name):
    print(f"Hello, {name}!")
greet("Alice")

from contextlib import contextmanager
@contextmanager
def my_context():
    print("Enter the context.")
    yield
    print("Exit the context.")
with my_context():
    print("Inside the context.")

class MyContext:
    def __enter__(self):
        print("Enter the context.")
    def __exit__(self, exc_type, exc_value, traceback):
        print("Exit the context.")
with MyContext():
    print("Inside the context.")

from functools import wraps
def my_decorator(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        print("Something is happening before the function is called.")
        result = func(*args, **kwargs)
        print("Something is happening after the function is called.")
        return result
    return wrapper
@my_decorator
def say_hello():
    """A docstring."""
    print("Hello!")
print(say_hello.__name__)  # 輸出 say_hello
print(say_hello.__doc__)   # 輸出 A docstring.

# my_utils.py
def add_prefix(prefix, text):
    """Add a prefix to text."""
    return f"{prefix} {text}"
def multiply_by_two(number):
    """Multiply a number by two."""
    return number * 2

import my_utils
text = my_utils.add_prefix("Hello", "World!")
result = my_utils.multiply_by_two(5)
print(text)    # 輸出 Hello World!
print(result)  # 輸出 10