Two other code paths where it makes sense for timeout to be a float are:

1. In poll_ignore_interrupts where timeout is multiplied by 1000 to get a value in milliseconds for passing to select.poll.poll:

   timeout_ms = None if timeout is None else timeout * 1000
   results = poller.poll(timeout_ms)
   

   If timeout is required to be int then it is impossible to specify sub-second timeouts even though these are supported by select.poll.poll.

2. In select_ignore_interrupts where timeout is passed to select.select:

   return select.select(iwtd, owtd, ewtd, timeout)
   

   The select.select documentation says, "The optional timeout argument specifies a time-out as a floating point number in seconds".