def create_invoices(invoices)
      b = Builder::XmlMarkup.new
      request_xml = b.Invoices {
        invoices.each do | invoice |
          invoice.to_xml(b)
        end
      }

      response_xml = http_put(@client, "#{@xero_url}/Invoices?SummarizeErrors=false", request_xml, {})

      response = parse_response(response_xml, {:request_xml => request_xml}, {:request_signature => 'PUT/invoices'})
      response.invoices.each_with_index do | response_invoice, index |
        invoices[index].invoice_id = response_invoice.invoice_id if response_invoice && response_invoice.invoice_id
      end
      response
    end
def create_invoices(invoices)
      b = Builder::XmlMarkup.new
      request_xml = b.Invoices {
        invoices.each do | invoice |
          invoice.to_xml(b)
        end
      }

      response_xml = http_put(@client, "#{@xero_url}/Invoices?SummarizeErrors=false", request_xml, {})

      response = parse_response(response_xml, {:request_xml => request_xml}, {:request_signature => 'PUT/invoices'})
      response.invoices.each_with_index do | response_invoice, index |
        invoices[index].invoice_id = response_invoice.invoice_id if response_invoice && response_invoice.invoice_id
      end
      response
    end
Creates an array of invoices with a single API request.

 Usage :
  invoices = [XeroGateway::Invoice.new(...), XeroGateway::Invoice.new(...)]
  result = gateway.create_invoices(invoices)