My guess would be the docs for socket.recv()[1], which indeed don't mention what the return value is after a socket has been closed, nor can I find that info elsewhere on that page.

Those docs for socket generally avoid going into detail, including specifically regarding returned values.  Apparently the approach is that this general note about the class explains where to look for more info:

"Socket objects have the following methods. Except for makefile(), these correspond to Unix system calls applicable to sockets."

Given this, I don't think adding this one small detail would be in line with the existing approach to documenting the socket class.


..[1]: https://docs.python.org/3/library/socket.html#socket.socket.recv