How to use the mongodb-client-encryption.extension function in mongodb-client-encryption

initializeFilter(client, context, callback) {
    const AWS_ACCESS_KEY_ID = process.env.AWS_ACCESS_KEY_ID;
    const AWS_SECRET_ACCESS_KEY = process.env.AWS_SECRET_ACCESS_KEY;
    let mongodbClientEncryption;
    try {
      mongodbClientEncryption = require('mongodb-client-encryption').extension(mongodb);
    } catch (e) {
      // Do Nothing
    }

    this.enabled = !!(AWS_ACCESS_KEY_ID && AWS_SECRET_ACCESS_KEY && mongodbClientEncryption);

    // Adds these fields onto the context so that they can be reused by tests
    context.clientSideEncryption = {
      enabled: this.enabled,
      mongodbClientEncryption,
      AWS_ACCESS_KEY_ID,
      AWS_SECRET_ACCESS_KEY
    };

    callback();
  }

} catch (err) {
      callback(
        new MongoError(
          'Auto-encryption requested, but the module is not installed. Please add `mongodb-client-encryption` as a dependency of your project'
        )
      );
      return;
    }
    try {
      let mongodbClientEncryption = require('mongodb-client-encryption');
      if (typeof mongodbClientEncryption.extension !== 'function') {
        throw new MongoError(
          'loaded version of `mongodb-client-encryption` does not have property `extension`. Please make sure you are loading the correct version of `mongodb-client-encryption`'
        );
      }
      AutoEncrypter = mongodbClientEncryption.extension(require('../../index')).AutoEncrypter;
    } catch (err) {
      callback(err);
      return;
    }

    const mongoCryptOptions = Object.assign({}, options.autoEncryption);
    topology.s.options.autoEncrypter = new AutoEncrypter(mongoClient, mongoCryptOptions);
    topology.s.options.autoEncrypter.init(err => {
      if (err) return callback(err, null);
      callback(null, topology);
    });
  });
}

} catch (err) {
      callback(
        new MongoError(
          'Auto-encryption requested, but the module is not installed. Please add `mongodb-client-encryption` as a dependency of your project'
        )
      );
      return;
    }
    try {
      let mongodbClientEncryption = require('mongodb-client-encryption');
      if (typeof mongodbClientEncryption.extension !== 'function') {
        throw new MongoError(
          'loaded version of `mongodb-client-encryption` does not have property `extension`. Please make sure you are loading the correct version of `mongodb-client-encryption`'
        );
      }
      AutoEncrypter = mongodbClientEncryption.extension(require('../../index')).AutoEncrypter;
    } catch (err) {
      callback(err);
      return;
    }

    const mongoCryptOptions = Object.assign({}, options.autoEncryption);
    topology.s.options.autoEncrypter = new AutoEncrypter(mongoClient, mongoCryptOptions);
    topology.s.options.autoEncrypter.init(err => {
      if (err) return callback(err, null);
      callback(null, topology);
    });
  });
}