docs: def _ValidateReturnValue(return_value, type_check_dict):
    """Validate return value and return list of errors messages."""
    return_check = type_check_dict.get("returns", None)
    if not return_check:
      return []
  
    messages = []
    if not _ValidateValue(return_value, return_check):
      message = ("Invalid return value '%s'. Expected %s" %
                 (return_value, _FormatTypeCheck(return_check)))
      messages.append(message)
    return messages