How to use the google-ads-node.CustomerOperation function in google-ads-node

public async update(customer: Customer, options?: ServiceCreateOptions): UpdateResponse {
        const request = new grpc.MutateCustomerRequest()
        const operation = new grpc.CustomerOperation()

        const pb = this.buildResource('Customer', customer) as grpc.Customer
        operation.setUpdate(pb)

        const mask = getFieldMask(customer)
        operation.setUpdateMask(mask)

        request.setCustomerId(this.cid)
        request.setOperation(operation)

        if (options && options.hasOwnProperty('validate_only')) {
            request.setValidateOnly(options.validate_only as boolean)
        }

        await this.service.mutateCustomer(request)
    }