code: function runRouteChat(callback) {
    var call = client.routeChat();
    call.on('data', function(note) {
      console.log('Got message "' + note.getMessage() + '" at ' +
          note.getLocation().getLatitude() + ', ' +
          note.getLocation().getLongitude());
    });
  
    call.on('end', callback);
  
    var notes = [{
      location: {
        latitude: 0,
        longitude: 0
      },
      message: 'First message'
    }, {
      location: {
        latitude: 0,
        longitude: 1
      },
      message: 'Second message'
    }, {
      location: {
        latitude: 1,
        longitude: 0
      },
      message: 'Third message'
    }, {
      location: {
        latitude: 0,
        longitude: 0
      },
      message: 'Fourth message'
    }];
    for (var i = 0; i < notes.length; i++) {
      var note = notes[i];
      console.log('Sending message "' + note.message + '" at ' +
          note.location.latitude + ', ' + note.location.longitude);
      var noteMsg = new messages.RouteNote();
      noteMsg.setMessage(note.message);
      var location = new messages.Point();
      location.setLatitude(note.location.latitude);
      location.setLongitude(note.location.longitude);
      noteMsg.setLocation(location);
      call.write(noteMsg);
    }
    call.end();
  }
docs: Run the routeChat demo. Send some chat messages, and print any chat messages
  that are sent from the server.
  @param {function} callback Called when the demo is complete