def __sub__(self, other):
        '''
        It is possible to subtract Duration and timedelta objects from Duration
        objects.
        '''
        if isinstance(other, Duration):
            newduration = Duration(years=self.years - other.years,
                                   months=self.months - other.months)
            newduration.tdelta = self.tdelta - other.tdelta
            return newduration
        try:
            # do maths with our timedelta object ....
            newduration = Duration(years=self.years, months=self.months)
            newduration.tdelta = self.tdelta - other
            return newduration
        except TypeError:
            # looks like timedelta - other is not implemented
            pass
        return NotImplemented

        It is possible to subtract Duration and timedelta objects from Duration
        objects.
        
Solutions/CyberArkAudit/Data Connectors/.python_packages/lib/site-packages/isodate/duration.py