code: def save(self, *args, **kwargs):
          
          from organizations.exceptions import OrganizationMismatch
  
          if self.organization_user.organization.pk != self.organization.pk:
              raise OrganizationMismatch
          else:
              super(AbstractBaseOrganizationOwner, self).save(*args, **kwargs)
docs: Extends the default save method by verifying that the chosen
          organization user is associated with the organization.
  
          Method validates against the primary key of the organization because
          when validating an inherited model it may be checking an instance of
          `Organization` against an instance of `CustomOrganization`. Mutli-table
          inheritence means the database keys will be identical though.