code: func (client *Client) UpdateSpaceIsolationSegmentRelationship(spaceGUID string, isolationSegmentGUID string) (Relationship, Warnings, error) {
  	body, err := json.Marshal(Relationship{GUID: isolationSegmentGUID})
  	if err != nil {
  		return Relationship{}, nil, err
  	}
  
  	request, err := client.newHTTPRequest(requestOptions{
  		RequestName: internal.PatchSpaceRelationshipIsolationSegmentRequest,
  		URIParams:   internal.Params{"space_guid": spaceGUID},
  		Body:        bytes.NewReader(body),
  	})
  	if err != nil {
  		return Relationship{}, nil, err
  	}
  
  	var relationship Relationship
  	response := cloudcontroller.Response{
  		DecodeJSONResponseInto: &relationship,
  	}
  
  	err = client.connection.Make(request, &response)
  	return relationship, response.Warnings, err
  }
docs: // UpdateSpaceIsolationSegmentRelationship assigns an isolation segment to a space and
  // returns the relationship.