code: function runListFeatures(callback) {
    var rectangle = {
      lo: {
        latitude: 400000000,
        longitude: -750000000
      },
      hi: {
        latitude: 420000000,
        longitude: -730000000
      }
    };
    console.log('Looking for features between 40, -75 and 42, -73');
    var call = client.listFeatures(rectangle);
    call.on('data', function(feature) {
        console.log('Found feature called "' + feature.name + '" at ' +
            feature.location.latitude/COORD_FACTOR + ', ' +
            feature.location.longitude/COORD_FACTOR);
    });
    call.on('end', callback);
  }
docs: Run the listFeatures demo. Calls listFeatures with a rectangle containing all
  of the features in the pre-generated database. Prints each response as it
  comes in.
  @param {function} callback Called when this demo is complete