Coroutines & asyncio.run — Series 2

Preview — 3 of 10 questions

What is the output of the following code?

javascript

import asyncio

async def count_up(n):
    for i in range(n):
        await asyncio.sleep(0)
        yield i

async def main():
    result = []
    async for x in count_up(3):
        result.append(x)
    print(result)

asyncio.run(main())

A[] — an async def function containing yield cannot be iterated with async for.

B<async_generator object count_up at 0x...>

CTypeError: 'async_generator' object is not iterable

D[0, 1, 2]

What is the output of the following code?

javascript

import asyncio

async def compute():
    return 42

async def main():
    coro = compute()
    print(await coro)
    print(await coro)

asyncio.run(main())

A42, then RuntimeError: cannot reuse already awaited coroutine

B42, then 42 — coroutine objects can be awaited repeatedly, each time re-running the body from scratch.

C42, then None — awaiting an already-completed coroutine a second time silently returns None.

DTypeError: coroutine.send() called on an exhausted coroutine

What is the output of the following code?

javascript

import asyncio

async def compute():
    return 1

coro = compute()
print(asyncio.iscoroutine(coro))
print(asyncio.iscoroutine(compute))

AFalse, True — iscoroutine checks the function itself, not the object it produces when called.

BTrue, False

CTrue, True

DFalse, False

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