How to use the nunjucks.lib function in nunjucks

constructor(app) {
    const fileLoader = new FileLoader(app);
    super(fileLoader, app.config.nunjucks);

    this.app = app;

    this[LOAD_FILTER]();

    // monkey patch `escape` with `app.helper.escape` provided by `egg-security` for better performance
    nunjucks.lib.escape = app.Helper.prototype.escape;

    // http://disse.cting.org/2016/08/02/2016-08-02-sandbox-break-out-nunjucks-template-engine
    const originMemberLookup = nunjucks.runtime.memberLookup;
    nunjucks.runtime.memberLookup = function(...args) {
      const val = args[1];
      if (val === 'prototype' || val === 'constructor') return null;
      return originMemberLookup(...args);
    };

    this.ViewHelper = createHelper(app, this.filters);
  }

const Promise = require('bluebird');
const Path = require('path');
const nunjucks = require('nunjucks');
const yaml = require('js-yaml');
const _ = require('lodash');
const requireAll = require('require-all');
const Log = require('../../core/log');
const WebError = require('../error');
const extensions = requireAll(`${__dirname}/extensions`);
const filters = requireAll(`${__dirname}/filters`);
const globals = requireAll(`${__dirname}/globals`);

const templateError = nunjucks.lib.TemplateError;
let lastError = null;

nunjucks.lib.TemplateError = function (message, lineno, colno) {
    if (message instanceof WebError) {
        message.lineno = lineno;
        message.colno = colno;
        lastError = message;
        throw message;
    }

    const err = new templateError(message, lineno, colno);

    lastError = err;

    return err;
};

module.exports = class Engine {

'use strict';

const Promise = require('bluebird');
const Path = require('path');
const nunjucks = require('nunjucks');
const yaml = require('js-yaml');
const _ = require('lodash');
const requireAll = require('require-all');
const Log = require('../../core/log');
const WebError = require('../error');
const extensions = requireAll(`${__dirname}/extensions`);
const filters = requireAll(`${__dirname}/filters`);
const globals = requireAll(`${__dirname}/globals`);

const templateError = nunjucks.lib.TemplateError;
let lastError = null;

nunjucks.lib.TemplateError = function (message, lineno, colno) {
    if (message instanceof WebError) {
        message.lineno = lineno;
        message.colno = colno;
        lastError = message;
        throw message;
    }

    const err = new templateError(message, lineno, colno);

    lastError = err;

    return err;
};