def _GetCompressedStreamTypes(self, mediator, path_spec):
    """Determines if a data stream contains a compressed stream such as: gzip.

    Args:
      mediator (ParserMediator): mediates the interactions between
          parsers and other components, such as storage and abort signals.
      path_spec (dfvfs.PathSpec): path specification of the data stream.

    Returns:
      list[str]: dfVFS compressed stream type indicators found in
          the data stream.
    """
    try:
      type_indicators = analyzer.Analyzer.GetCompressedStreamTypeIndicators(
          path_spec, resolver_context=mediator.resolver_context)
    except IOError as exception:
      type_indicators = []

      warning_message = (
          'analyzer failed to determine compressed stream type indicators '
          'with error: {0!s}').format(exception)
      mediator.ProduceExtractionWarning(warning_message, path_spec=path_spec)

    return type_indicators