Python's builtin asyncio Loop always returns a TimerHandle from call_later/call_at, however current uvloop will instead fall back to call_soon if delay==0. It seems desirable that uvloop be api-compatible. I'm sure there's a little performance improvement from call_soon if you can use it, but end-users call always use call_soon anyway if they know the delay is zero.

Demonstration:

import asyncio, uvloopasyncio.new_event_loop().call_later(0, lambda : None).when()uvloop.new_event_loop().call_later(0, lambda : None).when()