How to use the @braintree/event-emitter.call function in @braintree/event-emitter

function Dropin(options) {
  this._client = options.client;
  this._componentID = uuid();
  this._dropinWrapper = document.createElement('div');
  this._dropinWrapper.id = 'braintree--dropin__' + this._componentID;
  this._dropinWrapper.setAttribute('data-braintree-id', 'wrapper');
  this._dropinWrapper.style.display = 'none';
  this._dropinWrapper.className = 'braintree-loading';
  this._merchantConfiguration = options.merchantConfiguration;

  EventEmitter.call(this);
}

debug: isDebug,
    assetsUrl: assetsUrl,
    name: 'Hosted Fields'
  });

  hostedFieldsUrl = composeUrl(assetsUrl, componentId, isDebug);

  if (!options.fields || Object.keys(options.fields).length === 0) {
    throw new BraintreeError({
      type: sharedErrors.INSTANTIATION_OPTION_REQUIRED.type,
      code: sharedErrors.INSTANTIATION_OPTION_REQUIRED.code,
      message: 'options.fields is required when instantiating Hosted Fields.'
    });
  }

  EventEmitter.call(this);

  this._injectedNodes = [];
  this._destructor = new Destructor();
  this._fields = fields;
  this._state = {
    fields: {},
    cards: getCardTypes('')
  };

  this._bus = new Bus({
    channel: componentId,
    merchantUrl: location.href
  });

  this._destructor.registerFunctionForTeardown(function () {
    self._bus.teardown();

function PaymentRequestComponent(options) {
  var enabledPaymentMethods = options.enabledPaymentMethods || {};

  EventEmitter.call(this);

  this._componentId = uuid();
  this._client = options.client;
  this._enabledPaymentMethods = {
    basicCard: enabledPaymentMethods.basicCard !== false,
    googlePay: enabledPaymentMethods.googlePay !== false
  };
  this._googlePayVersion = options.googlePayVersion === 2 ? 2 : 1;
  this._googleMerchantId = BRAINTREE_GOOGLE_PAY_MERCHANT_ID;
  this._supportedPaymentMethods = this._constructDefaultSupportedPaymentMethods();
  this._defaultSupportedPaymentMethods = Object.keys(this._supportedPaymentMethods).map(function (key) {
    return this._supportedPaymentMethods[key];
  }.bind(this));
  this._bus = new Bus({channel: this._componentId});
}

function DropinModel(options) {
  this.componentID = options.componentID;
  this.merchantConfiguration = options.merchantConfiguration;

  this.isGuestCheckout = isGuestCheckout(options.client);

  this.dependenciesInitializing = 0;
  this.dependencySuccessCount = 0;
  this.failedDependencies = {};
  this._options = options;
  this._setupComplete = false;

  EventEmitter.call(this);
}

function EventedModel() {
  EventEmitter.call(this);

  this._attributes = this.resetAttributes();
}

function ThreeDSecure(options) {
  var self = this;
  var Framework = FRAMEWORKS[options.framework];

  EventEmitter.call(this);

  this._framework = new Framework(options);
  this._framework.setUpEventListeners(function () {
    self._emit.apply(self, arguments);
  });
}