Bus_. If `main_loop` is :const:`True` and no
	D-Bus main loop is registered yet, registers a default main loop
	(PyQt5 main loop if `use_qt_loop` is :const:`True`, otherwise GLib
	main loop).

	.. _SessionBus: https://www.freedesktop.org/wiki/IntroductionToDBus/#buses

	.. note::
	   Qt uses GLib main loops on UNIX-like systems by default, so one
	   will rarely need to set `use_qt_loop` to :const:`True`.
	r