public Path file(String key, String description) {
    String value = getRequiredArg(key, description);
    Path file = Path.of(value);
    logArgValue(key, description, file);
    return file;
  }
Returns a {@link Path} parsed from {@code key} argument which may or may not exist.
planetiler-core/src/main/java/com/onthegomap/planetiler/config/Arguments.java