dep of several aio-libs projects, include aiosignal (not in d-l-py yet), and aiohttp which is already in d-l-py, and I activated most of its tests recently, but some are still broken due this and other packaging bugs. It is also an exposed datatype of aiohttp, so this library is needed by users of the relevant part of aiohttp, and they will be expecting it pre-installed by aiohttp.