docs: def open(self, url, quality):
          """Attempt to open stream from *url*.
  
          Exits with '-1' (using self.exit()) in case of error, including
          an error msg.
          """
  
          self.original_url = url
          try:
              self.livestreamer = Livestreamer()
              self._load_config()
              streams = self.livestreamer.streams(url)
          except NoPluginError:
              self.exit("Livestreamer is unable to handle the URL '{}'".
                        format(url))
          except PluginError as err:
              self.exit("Plugin error: {}".format(err))
  
          if quality not in streams:
              print("Unable to find '{}' stream on URL '{}'"
                    .format(quality, url), file=sys.stderr)
              self.exit("List of available streams: {}".
                        format(sorted(streams.keys())))
  
          self.stream = streams[quality]
          try:
              self.fd = self.stream.open()
          except StreamError as err:
              self.exit("Failed to open stream: {}".format(err))