code: def _update_hosting_device_exclusivity(self, context, hosting_device,
                                             tenant_id):
          
          with context.session.begin(subtransactions=True):
              hosting_device['tenant_bound'] = tenant_id
              context.session.add(hosting_device)
              for item in (context.session.query(hd_models.SlotAllocation).
                           filter_by(hosting_device_id=hosting_device['id'])):
                  item['tenant_bound'] = tenant_id
                  context.session.add(item)
docs: Make <hosting device> bound or unbound to <tenant_id>.
  
          If <tenant_id> is None the device is unbound, otherwise it gets bound
          to that <tenant_id>