How to use the numbro.defaultFormat function in numbro

let start   = new Date().getTime();
let conf    = require('./conf').conf;
let Iconv   = require('iconv').Iconv;
let iconv   = new Iconv('GBK', 'UTF-8//TRANSLIT//IGNORE');
let request = require('request');
let Common  = require('./common').Common;

let from = null;
let to   = null;
let ft   = conf.fmt;

numbro.culture('zh-CN', conf.numbro);
// switch between languages
numbro.culture('zh-CN');
numbro.zeroFormat('N/A');
numbro.defaultFormat(ft.common);

/**
 * 各类提示信息
 * @type {Object}
 */
const MSG = {
    NO_TRADING      : '在当前时间范围内无董监高交易记录！',
    PARAM_ERROR     : '参数输入错误，请检查后重试！',
    INPUT_ERROR     : '输入错误，当前只支持通过单只证券代码查询，请重新输入！',
    REQUEST_ERROR   : '数据请求错误，请重试！错误信息：\n',
    SYSTEM_BUSY     : '系统正忙，请稍后再试!\n',
    SHOW_DETAIL_TIP : '  具体交易记录省略，可通过 "--show-detail" 参数查看详情...',
};

const MISC_QUERY_KEY = 'uzfin.com';