docs: def deep_force_unicode(value):
      """
      Recursively call force_text on value.
      """
      if isinstance(value, (list, tuple, set)):
          value = type(value)(map(deep_force_unicode, value))
      elif isinstance(value, dict):
          value = type(value)(map(deep_force_unicode, value.items()))
      elif isinstance(value, Promise):
          value = force_text(value)
      return value