How to use the dialogflow.SessionEntityTypesClient function in dialogflow

import * as dialogflow from "dialogflow";

const agentsClient = new dialogflow.AgentsClient();
const contextsClient = new dialogflow.ContextsClient();
const entityTypesClient = new dialogflow.EntityTypesClient();
const intentsClient = new dialogflow.IntentsClient();
const sessionEntityTypesClient = new dialogflow.SessionEntityTypesClient();
const sessionsClient = new dialogflow.SessionsClient();

// TODO: Add real significant tests

async function listSessionEntityTypes(projectId, sessionId) {
  // Imports the Dialogflow library
  const dialogflow = require('dialogflow');

  // Instantiates clients
  const sessionEntityTypesClient = new dialogflow.SessionEntityTypesClient();
  const sessionPath = sessionEntityTypesClient.sessionPath(
    projectId,
    sessionId
  );

  const request = {
    parent: sessionPath,
  };

  // Send the request for retrieving the sessionEntityType.
  const [response] = await sessionEntityTypesClient.listSessionEntityTypes(
    request
  );
  response.forEach(sessionEntityType => {
    console.log(`Session entity type name: ${sessionEntityType.name}`);
    console.log(`Number of entities: ${sessionEntityType.entities.length}\n`);

async function deleteSessionEntityType(
  projectId,
  sessionId,
  entityTypeDisplayName
) {
  // Imports the Dialogflow library
  const dialogflow = require('dialogflow');

  // Instantiates clients
  const sessionEntityTypesClient = new dialogflow.SessionEntityTypesClient();

  // The path to identify the sessionEntityType to be deleted.
  const sessionEntityTypePath = sessionEntityTypesClient.sessionEntityTypePath(
    projectId,
    sessionId,
    entityTypeDisplayName
  );

  const request = {
    name: sessionEntityTypePath,
  };

  // Send the request for retrieving the sessionEntityType.
  const result = await sessionEntityTypesClient.deleteSessionEntityType(
    request
  );

async function createSessionEntityType(
  projectId,
  sessionId,
  entityValues,
  entityTypeDisplayName,
  entityOverrideMode
) {
  // Imports the Dialogflow library
  const dialogflow = require('dialogflow');

  // Instantiates clients
  const sessionEntityTypesClient = new dialogflow.SessionEntityTypesClient();

  const sessionPath = sessionEntityTypesClient.sessionPath(
    projectId,
    sessionId
  );
  const sessionEntityTypePath = sessionEntityTypesClient.sessionEntityTypePath(
    projectId,
    sessionId,
    entityTypeDisplayName
  );

  // Here we use the entity value as the only synonym.
  const entities = [];
  entityValues.forEach(entityValue => {
    entities.push({
      value: entityValue,