How to use the apollo-server.buildSchemaFromTypeDefinitions function in apollo-server

FanoutGraphqlEpcpPublishesForPubSubEnginePublish,
  FanoutGraphqlGripChannelsForSubscription,
  FanoutGraphqlTypeDefs,
} from "../FanoutGraphqlApolloConfig";

/**
 * WebSocket-Over-HTTP Support requires storage to keep track of ws-over-http connections and subscriptions.
 * The Storage objects match an ISimpleTable interface that is a subset of the @pulumi/cloud Table interface. MapSimpleTable is an in-memory implementation, but you can use @pulumi/cloud implementations in production, e.g. to use DyanmoDB.
 */
const webSocketOverHttpStorage = {
  connections: MapSimpleTable(),
  subscriptions: MapSimpleTable(),
};

// Build a schema from typedefs here but without resolvers (since they will need the resulting pubsub to publish to)
const schema = buildSchemaFromTypeDefinitions(FanoutGraphqlTypeDefs(true));

// This is what you need to support EPCP Publishes (make sure it gets to your resolvers who call pubsub.publish)
const pubsub = EpcpPubSubMixin({
  epcpPublishForPubSubEnginePublish: FanoutGraphqlEpcpPublishesForPubSubEnginePublish(
    { schema, subscriptions: webSocketOverHttpStorage.subscriptions },
  ),
  grip: {
    url: process.env.GRIP_URL || "http://localhost:5561",
  },
  // Build a schema from typedefs here but without resolvers (since they will need the resulting pubsub to publish to)
  schema,
})(new PubSub());

const apolloServer = new ApolloServer(
  FanoutGraphqlApolloConfig({
    pubsub,