code: func (c *Client) PlanList(addonServiceIdentity string, lr *ListRange) ([]Plan, error) {
  	req, err := c.NewRequest("GET", "/addon-services/"+addonServiceIdentity+"/plans", nil, nil)
  	if err != nil {
  		return nil, err
  	}
  
  	if lr != nil {
  		lr.SetHeader(req)
  	}
  
  	var plansRes []Plan
  	return plansRes, c.DoReq(req, &plansRes)
  }
docs: // List existing plans.
  //
  // addonServiceIdentity is the unique identifier of the Plan's AddonService. lr
  // is an optional ListRange that sets the Range options for the paginated list
  // of results.