code: function listen (stream_url, options, callback) {
      if (options && options.constructor===Function) {
          callback = options;
          options = undefined;
      }
      var u = url.parse(stream_url.toString());
      var proto = u.protocol.substr(0, u.protocol.length-1);
      var adaptor = adaptors[proto];
      if (!adaptor) {
          throw new Error('protocol unknown: '+u.protocol);
      }
      return adaptor.listen(u, options, callback);
  }
docs: returns some "handler object" that has .close() method and emits 'connection' event