// Get the localized item of a given key inside a data dictionary, using the
// provided language.
#let localize(data, key, language) = {
  // If the key is directly available in the data then it hasn't been localized.
  if key in data {
    return data.at(key)
  }

  // Then check for the key with the wanted language appended to it.
  let key_with_language = key + "_" + language
  if key_with_language in data {
    return data.at(key_with_language)
  }

  // If a locale dictionary exists in the data, then run this function again
  // using that dictionary for the same key and language.
  if "locale" in data {
    return localize(data.locale, key, language)
  }

  // And if the key nor locale exists in any way then panic, as we won't have
  // any text to return.
  panic("Data does not contain key in any localized way: " + key, data)
}