code: public InvoiceData getInvoice(int year, int month, String pricingAccountAlias) {
          return client.getInvoice(year, month, pricingAccountAlias);
      }
docs: Gets a list of invoicing data for a given account alias for a given month.
  @param year Year of usage
  @param month Monthly period of usage
  @param pricingAccountAlias Short code of the account that sends the invoice for the accountAlias
  @return the invoice data