How to use the markdown-it.set function in markdown-it

var Promise = require('bluebird'),
    nconf = require('nconf'),
    htmlToText = require('html-to-text'),
    fsp = require('fs-extra'),
    path = require('path'),
    fs = require('fs'),
    logger = require('../utils/logger'),
    sequelize = require('sequelize'),
    md = require('markdown-it')('zero') // 'zero' preset deletes all config but essential features
        .set({ breaks: true })
        .enable([ 'emphasis', 'link', 'newline' ]),
        // In case we want to add more rules to be parsed, check :
        // https://github.com/markdown-it/markdown-it/tree/8.3.1/lib
        // parser_block.js, parser_core.js, parser_inline.js

    searchEngineLang = nconf.get('app').searchEngineLang,
    defaultPageSize = nconf.get('app').defaultPageSize,
    answersRequestType = {
        'normal': 0,
        'full': 1,
        'anonymized': 2
    },
    sqlType = {
        'select': 0,
        'ddl': 1