def add_context(self, isc_name, isc_policy_id, isc_traffic_tag):
        """
        Create the VSS Context within the VSSContainer

        :param str isc_name: ISC name, possibly append policy name??
        :param str isc_policy_id: Policy ID in SMC (the 'key' attribute)
        :param str isc_traffic_tag: NSX groupId (serviceprofile-145)
        :raises CreateElementFailed: failed to create
        :return: VSSContext
        """
        if 'add_context' in self.data.links: # SMC >=6.5
            element = ElementCreator(
                VSSContext,
                href=self.get_relation('add_context'),
                json = {
                    'name': isc_name,
                    'vc_isc': {
                        'isc_name': isc_name,
                        'isc_policy_id': isc_policy_id,
                        'isc_traffic_tag': isc_traffic_tag
                    }
                })
        else: # SMC < 6.5
            element = VSSContext.create(
                isc_name=isc_name,
                isc_policy_id=isc_policy_id,
                isc_traffic_tag=isc_traffic_tag,
                vss_container=self)
        
        # Delete cache since the virtualResources node is attached to
        # the engine json
        self._del_cache()
        return element