def getWorksheet(self):
        """Returns the Worksheet to which this analysis belongs to, or None
        """
        worksheet = self.getBackReferences('WorksheetAnalysis')
        if not worksheet:
            return None
        if len(worksheet) > 1:
            logger.error(
                "Analysis %s is assigned to more than one worksheet."
                % self.getId())
        return worksheet[0]
Returns the Worksheet to which this analysis belongs to, or None