docs: def _parse_values(values, extra=None):
      """
      Utility function to flatten out args.
  
      For internal use only.
  
      :param values: list, tuple, or str
      :param extra: list or None
      :return: list
      """
      coerced = list(values)
  
      if coerced == values:
          values = coerced
      else:
          coerced = tuple(values)
          if coerced == values:
              values = list(values)
          else:
              values = [values]
  
      if extra:
          values.extend(extra)
      return values