docs: def get_url(field):
      """Return file's url based on base url set in settings."""
      hydrated_path = _get_hydrated_path(field)
      base_url = getattr(settings, 'RESOLWE_HOST_URL', 'localhost')
      return "{}/data/{}/{}".format(base_url, hydrated_path.data_id, hydrated_path.file_name)