How to use the google-gax.grpc function in google-gax

this._descriptors = {};

    // Ensure that options include the service address and port.
    opts = Object.assign(
      {
        clientConfig: {},
        port: this.constructor.port,
        servicePath: this.constructor.servicePath,
      },
      opts
    );

    // Create a `gaxGrpc` object, with any grpc-specific options
    // sent to the client.
    opts.scopes = this.constructor.scopes;
    var gaxGrpc = gax.grpc(opts);

    // Save the auth object to the client, for use by other methods.
    this.auth = gaxGrpc.auth;

    // Determine the client header string.
    var clientHeader = [
      `gl-node/${process.version}`,
      `grpc/${gaxGrpc.grpcVersion}`,
      `gax/${gax.version}`,
      `gapic/${VERSION}`,
    ];
    if (opts.libName && opts.libVersion) {
      clientHeader.push(`${opts.libName}/${opts.libVersion}`);
    }

    // Load the applicable protos.

this._descriptors = {};

    // Ensure that options include the service address and port.
    opts = Object.assign(
      {
        clientConfig: {},
        port: this.constructor.port,
        servicePath: this.constructor.servicePath,
      },
      opts
    );

    // Create a `gaxGrpc` object, with any grpc-specific options
    // sent to the client.
    opts.scopes = this.constructor.scopes;
    var gaxGrpc = gax.grpc(opts);

    // Save the auth object to the client, for use by other methods.
    this.auth = gaxGrpc.auth;

    // Determine the client header string.
    var clientHeader = [
      `gl-node/${process.version.node}`,
      `grpc/${gaxGrpc.grpcVersion}`,
      `gax/${gax.version}`,
      `gapic/${VERSION}`,
    ];
    if (opts.libName && opts.libVersion) {
      clientHeader.push(`${opts.libName}/${opts.libVersion}`);
    }

    // Load the applicable protos.

function v1beta1(options) {
  options = extend(
    {
      scopes: v1beta1.ALL_SCOPES,
    },
    options
  );
  var gaxGrpc = gax.grpc(options);
  return firestoreClient(gaxGrpc);
}

* See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*!
 * @module monitoring
 * @name Monitoring
 */

'use strict';

var extend = require('extend');
var gapic = {
  v3: require('./v3')
};
var gaxGrpc = require('google-gax').grpc();

const VERSION = require('../package.json').version;

/**
 * Create a groupServiceClient with additional helpers for common
 * tasks.
 *
 * The Group API lets you inspect and manage your
 * [groups](https://cloud.google.comgoogle.monitoring.v3.Group).
 *
 * A group is a named filter that is used to identify
 * a collection of monitored resources. Groups are typically used to
 * mirror the physical and/or logical topology of the environment.
 * Because group membership is computed dynamically, monitored
 * resources that are started in the future are automatically placed
 * in matching groups. By using a group to name monitored resources in,