René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"17-futures/countries/flags_asyncio.py fails to download flags","articleBody":"When running with python 3.6.6, with aiohttp 3.3.2, the 'flags_asyncio.py' script outputs 20 pairs of lines similar to this:\r\n`Unclosed client session`\r\n`client_session: \u003caiohttp.client.ClientSession object at 0x10ecbfd68\u003e`\r\nfollowed by 20 tracebacks similar to this:\r\n`Task exception was never retrieved`\r\n`future: \u003cTask finished coro=\u003cdownload_one() done, defined at flags_asyncio.py:28\u003e` `exception=TypeError(\"'_SessionRequestContextManager' object is not iterable\",)\u003e`\r\n`Traceback (most recent call last):`\r\n` File \"flags_asyncio.py\", line 30, in download_one`\r\n`    image = yield from get_flag(cc)  # \u003c7\u003e`\r\n`  File \"flags_asyncio.py\", line 23, in get_flag`\r\n`    resp = yield from aiohttp.request('GET', url)  # \u003c4\u003e`\r\n`TypeError: '_SessionRequestContextManager' object is not iterable`\r\n","author":{"url":"https://github.com/cdm-work","@type":"Person","name":"cdm-work"},"datePublished":"2018-09-13T21:01:27.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/25/example-code/issues/25"}