code: func (r Product_Promotion) FindByPromoCode(code *string) (resp datatypes.Container_Product_Promotion, err error) {
  	params := []interface{}{
  		code,
  	}
  	err = r.Session.DoRequest("SoftLayer_Product_Promotion", "findByPromoCode", params, &r.Options, &resp)
  	return
  }
docs: // Retrieves a promotion using its code.