How to use the @f5devcentral/f5-cloud-libs.bigIp function in @f5devcentral/f5-cloud-libs

beforeEach(() => {
            executeBashCommandExec = doUtil.executeBashCommandExec;
            getCurrentPlatform = doUtil.getCurrentPlatform;
            bigIpMock = new BigIpMock();
            bigIpMock.list = () => Promise.resolve({
                value: 'none'
            });
        });

.then((data) => {
            credentials = data;
            masterBigIp = new BigIp({ loggerOptions: this.loggerOptions });
            return masterBigIp.init(
                mgmtIp,
                credentials.username,
                credentials.password,
                { port: mgmtPort || this.mgmtPort }
            );
        })
        .then(() => {

GceCloudProvider.prototype.bigIpReady = function bigIpReady() {
    if (this.clOptions.user && (this.clOptions.password || this.clOptions.passwordUrl)) {
        bigIp = new BigIp({ loggerOptions: this.loggerOptions });
        return bigIp.init(
            'localhost',
            this.clOptions.user,
            this.clOptions.password || this.clOptions.passwordUrl,
            {
                port: parseInt(this.mgmtPort, 10),
                passwordIsUrl: typeof this.clOptions.passwordUrl !== 'undefined',
                passwordEncrypted: this.clOptions.passwordEncrypted
            }
        )
            .then(() => {
                if (this.instancesToRevoke.length > 0) {
                    logger.debug('Revoking licenses of non-masters that are not known to GCE');
                    return this.revokeLicenses(this.instancesToRevoke, { bigIp });
                }
                return q();

getBigIp(callingLogger, options) {
        const optionalArgs = {};
        Object.assign(optionalArgs, options);
        const bigIp = new BigIp({ logger: callingLogger });
        return this.initializeBigIp(
            bigIp,
            optionalArgs.host || 'localhost',
            optionalArgs.port,
            optionalArgs.user || 'admin',
            optionalArgs.authToken || optionalArgs.password || 'admin',
            {
                passwordIsToken: !!optionalArgs.authToken
            }
        );
    },