How to use the vt-pbf.fromGeojsonVt function in vt-pbf

var layerCount = 0
  for (var layer in featuresByLayer) {
    var gridFeatures = aggregateCells(
      featuresByLayer[layer],
      tile,
      z + options._depth,
      options.aggregations[layer],
      options.postAggregations[layer])

    aggregatedLayers[layer] = tileFromFeatureCollection(gridFeatures, tile)
    layerCount++
  }

  // serialize, compress, and save the tile
  if (layerCount) {
    var buff = vtpbf.fromGeojsonVt(aggregatedLayers)
    zlib.gzip(buff, function (err, zipped) {
      if (err) { return next(err) }
      // console.log('putting', tile)
      db.putTile(tile[0], tile[1], tile[2], zipped, next)
    })
  } else {
    next()
  }
}

for (const feature of tile.features) {
                        for (const property in feature.tags) {
                            fields[property] = typeof feature.tags[property];
                        }
                    }
                    if (options.storeClusterExpansionZoom) {
                        for (const feature of tile.features) {
                            if (feature.tags.cluster_id) {
                                feature.tags['clusterExpansionZoom'] = clustered.getClusterExpansionZoom(feature.tags.cluster_id);
                            }
                        }
                    }

                    // Convert to PBF and compress before insertion
                    compressedTiles.push(
                        gzip(VTpbf.fromGeojsonVt({'geojsonLayer': tile}, {version: options.tileSpecVersion, extent: options.extent})).then((compressed) => {
                            if (compressed.length > 500000) {
                                return Promise.reject(new Error(`Tile z:${z}, x:${x}, y:${y} greater than 500KB compressed. Try increasing radius or max zoom, or try including fewer cluster properties.`));
                            }
                            statements.push(
                                db.run(
                                    'INSERT INTO tiles (zoom_level, tile_column, tile_row, tile_data) VALUES(?, ?, ?, ?)',
                                    z, x, zoomDimension - 1 - y, compressed));
                            return Promise.resolve();
                        })
                    );
                }
            }
        }

        // Complete metadata table by adding layer definition
        const vectorJson = {

let x = parseInt(p.x);
      let y = parseInt(p.y);
      let z = parseInt(p.z);
      let format = p.format;

      let tileData = await queryTile(z, x, y)
      logger.debug(JSON.stringify(tileData));
      let features = tileData.map(dbObjToGeoJSON);

      try {
        // Send a vector tile
        if (format === 'pbf') {
          if (features.length > 0) {
            const tileIndex = gvt(fc(features), {indexMaxZoom: z, maxZoom: z});
            const tile = tileIndex.getTile(z, x, y);
            let buf = vtpbf.fromGeojsonVt({ 'geojsonLayer': tile})
            res.writeHead(200, {
              'Content-Type': 'application/x-protobuf'
            });
            res.end(buf)
          } else {
            res.status(404).send();
          }
          // Send a GeoJSON array
        } else if (format === 'json'){
          res.json(features);
        } else {
          res.boom.badRequest('format must be pbf or json');
        }
      } catch (err) {
        logger.error(err);
        res.boom.badImplementation('server error!');

app.get('/:layer/:z/:x/:y.mvt', function (req, res) {
            var layer = req.params['layer'];
            if (!tileIndexes.hasOwnProperty(layer)) {
                send404(res);
            }
            var z = +req.params['z'];
            var x = +req.params['x'];
            var y = +req.params['y'];
            var tile = tileIndexes[layer].getTile(z, x, y);
            if (!tile || !tile.features) {
                return res.json({});
            }
            var buff = vtpbf.fromGeojsonVt({ 'geojsonLayer': tile });
            res.send(buff);
        });
        app.listen(httpPort, function () { return console.info("Tile service is listening on port " + httpPort); });

static async geoJSONs2VTPBF(geojsons, zoomLevel, column, row, extent) {

		const tiles = {};
		const layerNames = Object.keys(geojsons);
		await Utils.asyncForEach(layerNames, async (layerName) => {

			const tile = await DataConverter.geoJSON2MVTLayer(geojsons[layerName]);
			DataConverter.convertTileCoords(tile, zoomLevel, column, row, extent);
			tiles[layerName] = tile;

		});

		const buffer = vtpbf.fromGeojsonVt(tiles, {version: 2});
		const binBuffer = Buffer.from(buffer);

		return binBuffer;

	}

app.get('/:layer/:z/:x/:y.mvt', (req, res) => {
    const { tile } = getTile(req, res);
    if (!tile || !tile.features) {
      return;
    }
    /** Notice that I set the source-layer (for Mapbox GL) to all */
    res.send(Buffer.from(vtpbf.fromGeojsonVt({ all: tile })));
  });

geopackage.features(req.layer, req.params.tableName, tileParams, tileBuffer, function(err, featureCollection) {
          if (err) return next(err);

          const tileIndex = geojsonvt(featureCollection, {buffer: tileBuffer * 8, maxZoom: tileParams.z});
          const tile = tileIndex.getTile(tileParams.z, tileParams.x, tileParams.y);
          const vectorTile = vtpbf.fromGeojsonVt({ [table.name]: tile || { features: [] } });
          res.contentType('application/x-protobuf');
          res.send(Buffer.from(vectorTile));
        });
      } else {

features: features
    };
    var tileBuffer = 8;
    var tileIndex = geojsonvt(featureCollection, {buffer: tileBuffer * 8, maxZoom: z});
    var layer = {};
    var tile = tileIndex.getTile(z, x, y);

    var gjvt = {};

    if (tile) {
      gjvt[table] = tile;
    } else {
      gjvt[table] = {features:[]};
    }

    return vtpbf.fromGeojsonVt(gjvt);
  });
}

function getTile(z, x, y, tileIndex, options) {
    var tile = tileIndex.getTile(z, x, y);

    if (tile != null) {
        var pbfOptions = {};

        pbfOptions[options.layerName] = tile;
        var pbf = vtpbf.fromGeojsonVt(pbfOptions);

        return pbf;
    }

    return null;
};