First example given in documentation seems incomplete

[Kat154]

the following example seems incomplete in documentation:
import aiohttp
import asyncio
from aioresponses import aioresponses

@aioresponses()
def test_request(mocked):
loop = asyncio.get_event_loop()
mocked.get('http://example.com', status=200, body='test')
session = aiohttp.ClientSession()
resp = loop.run_until_complete(session.get('http://example.com'))

assert resp.status == 200
mocked.assert_called_once_with('http://example.com')

where is mocked defined as a fixture, perhaps im missing something feel free to point out.