One language.
All formats.

%utlx 1.0
input  xml   ← change to json, csv, yaml
output json
---
{
  invoice: {
    id:   "INV-" + $input.Order.@id,
    date: $input.Order.@date,

    customer: {
      name:  $input.Order.Customer.Name,
      email: $input.Order.Customer.Email
    },

    items: $input.Order.Items.Item
      |> map(item => {
           sku:   item.@sku,
           qty:   parseNumber(item.@quantity),
           total: parseNumber(item.@quantity)
                 * parseNumber(item.@price)
         }),

    total: sum($input.Order.Items.Item
      |> map(i => parseNumber(i.@qty)
                * parseNumber(i.@price)))
  }
}