Decorators

import time

def timed(func):
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        print(f"{func.__name__} took {time.time() - start:.3f}s")
        return result
    return wrapper

@timed
def slow_query():
    time.sleep(1)

A decorator wraps a function with extra behavior without changing its code. @timed is equivalent to writing slow_query = timed(slow_query) — decorators are just a cleaner syntax for that pattern.