code: function latencyWindowReducer(topologyDescription, servers) {
    const low = servers.reduce(
      (min, server) => (min === -1 ? server.roundTripTime : Math.min(server.roundTripTime, min)),
      -1
    );
  
    const high = low + topologyDescription.localThresholdMS;
  
    return servers.reduce((result, server) => {
      if (server.roundTripTime <= high && server.roundTripTime >= low) result.push(server);
      return result;
    }, []);
  }
docs: Reduces a list of servers to ensure they fall within an acceptable latency window. This is
  further specified in the "Server Selection" specification, found here:
  https://github.com/mongodb/specifications/blob/master/source/server-selection/server-selection.rst
  
  @param {topologyDescription} topologyDescription The topology description
  @param {ServerDescription[]} servers The list of servers to reduce
  @returns {ServerDescription[]} The servers which fall within an acceptable latency window