Currently, if you want to change the line buffering behaviour of standard streams, you can create a new stream and assign it to sys.{stdout,stderr,stdin}.  Unfortunately, it is common for references to the old streams to be stored in various places (such as logging configuration, or third-party libraries).  Replacing them all is probably a hopeless cause.  It would be much better if one could simply write `sys.stdout.line_buffering = True` and be done with it.