def remove_duplicates(self, ws):
        """When this analysis is unassigned from a worksheet, this function
        is responsible for deleting DuplicateAnalysis objects from the ws.
        """
        for analysis in ws.objectValues():
            if IDuplicateAnalysis.providedBy(analysis) \
                    and analysis.getAnalysis().UID() == self.UID():
                ws.removeAnalysis(analysis)
When this analysis is unassigned from a worksheet, this function
        is responsible for deleting DuplicateAnalysis objects from the ws.