docs: def _load_streams(self):
          """
          Reads, parses and creates streams specified in config.yaml.
          """
          common_err_msg = 'No valid {} stream configurations found. '
          specific_err_msg = {'inbound': 'No data will be received (or displayed).',
                              'outbound': 'No data will be published.'}
          err_msgs = {}
  
          for stream_type in ['inbound', 'outbound']:
              err_msgs[stream_type] = common_err_msg.format(stream_type) + specific_err_msg[stream_type]
              streams = ait.config.get('server.{}-streams'.format(stream_type))
  
              if streams is None:
                  log.warn(err_msgs[stream_type])
              else:
                  for index, s in enumerate(streams):
                      try:
                          if stream_type == 'inbound':
                              strm = self._create_inbound_stream(s['stream'])
                              if type(strm) == PortInputStream:
                                  self.servers.append(strm)
                              else:
                                  self.inbound_streams.append(strm)
                          elif stream_type == 'outbound':
                              strm = self._create_outbound_stream(s['stream'])
                              self.outbound_streams.append(strm)
                          log.info('Added {} stream {}'.format(stream_type, strm))
                      except Exception:
                          exc_type, value, tb = sys.exc_info()
                          log.error('{} creating {} stream {}: {}'.format(exc_type,
                                                                          stream_type,
                                                                          index,
                                                                          value))
          if not self.inbound_streams and not self.servers:
              log.warn(err_msgs['inbound'])
  
          if not self.outbound_streams:
              log.warn(err_msgs['outbound'])