def _prepair(self):
try:<EOL><INDENT>sessionbus = dbus.SessionBus()<EOL>systembus  = dbus.SystemBus()<EOL><DEDENT>except:<EOL><INDENT>return (None, None)<EOL><DEDENT>for dbus_props in self.DBUS_SHUTDOWN.values():<EOL><INDENT>try:<EOL><INDENT>if dbus_props['<STR_LIT>'] == SESSION_BUS:<EOL><INDENT>bus = sessionbus<EOL><DEDENT>else:<EOL><INDENT>bus = systembus<EOL><DEDENT>interface = bus.get_object(dbus_props['<STR_LIT>'],<EOL>dbus_props['<STR_LIT>'])<EOL>proxy = interface.get_dbus_method(dbus_props['<STR_LIT>'],<EOL>dbus_props['<STR_LIT>'])<EOL>return (proxy, dbus_props['<STR_LIT>'])<EOL><DEDENT>except dbus.exceptions.DBusException:<EOL><INDENT>continue<EOL><DEDENT><DEDENT>return (None, None)<EOL>
Try to connect to the given dbus services. If successful it will
        return a callable dbus proxy and those arguments.