code: def setDefaultFetcher(fetcher, wrap_exceptions=True):
      
      global _default_fetcher
      if fetcher is None or not wrap_exceptions:
          _default_fetcher = fetcher
      else:
          _default_fetcher = ExceptionWrappingFetcher(fetcher)
docs: Set the default fetcher
  
      @param fetcher: The fetcher to use as the default HTTP fetcher
      @type fetcher: HTTPFetcher
  
      @param wrap_exceptions: Whether to wrap exceptions thrown by the
          fetcher wil HTTPFetchingError so that they may be caught
          easier. By default, exceptions will be wrapped. In general,
          unwrapped fetchers are useful for debugging of fetching errors
          or if your fetcher raises well-known exceptions that you would
          like to catch.
      @type wrap_exceptions: bool