How to use the braintree-web/paypal-checkout.create function in braintree-web

var setupComplete = false;
  var self = this;
  var paypalType = isCredit ? 'paypalCredit' : 'paypal';
  var paypalConfiguration = this.model.merchantConfiguration[paypalType];

  this.paypalConfiguration = assign({}, paypalConfiguration);

  this.model.asyncDependencyStarting();
  asyncDependencyTimeoutHandler = setTimeout(function () {
    self.model.asyncDependencyFailed({
      view: self.ID,
      error: new DropinError('There was an error connecting to PayPal.')
    });
  }, ASYNC_DEPENDENCY_TIMEOUT);

  return btPaypal.create({client: this.client}).then(function (paypalInstance) {
    var checkoutJSConfiguration;
    var buttonSelector = '[data-braintree-id="paypal-button"]';
    var environment = self.client.getConfiguration().gatewayConfiguration.environment === 'production' ? 'production' : 'sandbox';
    var locale = self.model.merchantConfiguration.locale;

    self.paypalInstance = paypalInstance;

    self.paypalConfiguration.offerCredit = Boolean(isCredit);
    checkoutJSConfiguration = {
      env: environment,
      style: self.paypalConfiguration.buttonStyle || {},
      commit: self.paypalConfiguration.commit,
      payment: function () {
        return paypalInstance.createPayment(self.paypalConfiguration).catch(reportError);
      },
      onAuthorize: function (data) {