def CheckPreviousBarline(self, staff):
        """method which checks the bar before the current for changes we need to make to it's barlines"""
        measure_before_last = self.getMeasureAtPosition(-2, staff)
        last_measure = self.getMeasureAtPosition(-1, staff)
        if last_measure is not None and measure_before_last is not None:
            bline1 = measure_before_last.GetBarline("right")
            bline2 = last_measure.GetBarline("left")
            if bline1 is not None:
                if hasattr(bline1, "ending"):
                    if bline2 is not None:
                        if not hasattr(bline2, "ending"):
                            bline1.ending.type = "discontinue"
                    else:
                        bline1.ending.type = "discontinue"
method which checks the bar before the current for changes we need to make to it's barlines