When reading the documentation for call_soon(), call_later(), call_at(), and several other functions, the sentence that describes the return value is in passive voice:
https://docs.python.org/3/library/asyncio-eventloop.html

> An instance of asyncio.TimerHandle is returned which can be used to cancel the callback.

The problem:

Most functions in Python documentation describe the return value by "Return foobar", an active voice sentence at the beginning of a paragraph. (e.g. https://docs.python.org/3/library/functions.html ) Thus, for the reader, it's easy to quickly skim the text for the return value. Even easier because the reader is already trained to do so, given other occurrences in the documentation.

However, by hiding "is returned" in the middle of the sentence/paragraph, the reader can't easily find the return value, having to carefully read through all the text. Not only this is slower, but way more difficult if the reader is in a hurry or tired. (That was my case, I missed that sentence even after looking at the documentation several times.)

Solution:

Change it to: Return an instance of asyncio.TimerHandle which can be used to cancel the callback.

Further solution:

Search the documentation for other cases of "is returned" and consider if it is worth rewording as active voice.

Bonus link: https://developers.google.com/tech-writing/one/active-voice

Active voice is strongly recommended for docstrings in PEP 257 and commit messages somewhere in the Developer guide and applies to docs.  The doc for the asyncio call_x functions all start with the active voice: 'Schedule', which is the main action of the function.  'is returned' occurs later in the entries and that case is less clear.