code: def update(self, request, pk=None, parent_lookup_organization=None):
          '''Add a user to an organization.'''
          user = get_object_or_404(User, pk=pk)
          org = get_object_or_404(
              SeedOrganization, pk=parent_lookup_organization)
          self.check_object_permissions(request, org)
          org.users.add(user)
          return Response(status=status.HTTP_204_NO_CONTENTf update(self, request, pk=None, parent_lookup_organization=None):
          '''Add a user to an organization.'''
          user = get_object_or_404(User, pk=pk)
          org = get_object_or_404(
              SeedOrganization, pk=parent_lookup_organization)
          self.check_object_permissions(request, org)
          org.users.add(user)
          return Response(status=status.HTTP_204_NO_CONTENT)
docs: Add a user to an organization.