Could you explain what coroutines are and how they work?

Coroutines are special functions that can suspend their execution and later resume it, maintaining their state between calls. In Python, coroutines are often used for asynchronous programming and allow writing code that does not block execution while waiting for a result.

In Python, coroutines are created using the async def keyword and are managed with await. When a coroutine is called, it returns an object that can be run in an event loop.

Example of a simple coroutine:

import asyncio

async def say_hello():
    print("Hello")
    await asyncio.sleep(1)  # suspends execution for 1 second
    print("World")

asyncio.run(say_hello())

Here, await allows suspending the function without blocking the entire thread and resuming it after the asynchronous operation completes.