How to use the natural.stopwords function in natural

/*!
 * levels
 * Copyright(c) 2013 Eugene Ware 
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var natural = require('natural')
  , metaphone = natural.Metaphone.process
  , stem = natural.PorterStemmer.stem
  , stopwords = natural.stopwords
  , sublevel = require('level-sublevel')
  , _ = require('underscore')
  , async = require('async')
  , byteup = require('byteup')
  , noop = function(){};

/* Add bytewise encoding */
byteup();

/**
 * Library version.
 */

exports.version = '0.0.3';

/**

/*!
 * reds
 * Copyright(c) 2011 TJ Holowaychuk 
 * cn-search
 * Copyright(c) 2013 Sxyizhiren <786647787@qq.com>
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var natural = require('natural');
var metaphone = natural.Metaphone.process;
var stem = natural.PorterStemmer.stem;
var stopwords = natural.stopwords;
var cnstopwords = require('./cnstopWords');

// default chinese segment
var Segment = require('segment').Segment;
var segment = new Segment();
segment.useDefault();

/**
 * Chinese Segment
 * @type {*}
 */
var segmentSync = function(str){
    var words=segment.doSegment(str);
    var result=[];
    for(var i= 0,len=words.length;i

function stripStopWords(words, options) {
  var ret = [];
  options = options || {};
  var stopwords = options.stopwords || natural.stopwords;
  if (words) {
    for (var i = 0, len = words.length; i < len; ++i) {
      if (~stopwords.indexOf(words[i])) continue;
      ret.push(words[i]);
    }
  }
  return ret;
}

/*!
 * reds
 * Copyright(c) 2011 TJ Holowaychuk 
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var natural = require('natural');
var metaphone = natural.Metaphone.process;
var stem = natural.PorterStemmer.stem;
var stopwords = natural.stopwords;
var redis = require('redis');
function noop(){};

/**
 * Library version.
 */

exports.version = '1.0.0';

/**
 * Expose `Search`.
 */

exports.Search = Search;

/**

var fs = require('fs')
, levelup = require('levelup')
, natural = require('natural');

//Calibration values
//precalculate index metadata to save time ewith every query

//Arbitrary defaults
var maxStringFieldLength = 300;  //this has a really big effect on performance for some reason...
var maxMetadataFieldLength = 20;

//only use this global for fast reads when searching- NEVER WRITE TO IT
var indexMetaDataGlobal = readMetaDataGlobal();

var reverseIndex = levelup('./norchindex')
, stopwords = require('natural').stopwords
, TfIdf = require('natural').TfIdf;



exports.indexData = function(callback) {
  callback(readMetaDataGlobal());
}


exports.indexPeek = function(start, stop, callback) {
  var dump = '';
  reverseIndex.createReadStream({
    start:start + "~",
    end:stop + "~~"})
    .on('data', function(data) {
      dump += data.key + '<br>'

var stopwords = require('natural').stopwords;
var async = require('async');
var scontext = require('search-context');
var indexSize = 0;

exports.search = function (reverseIndex, docFreqIndex, q, callback) {

  docFreqIndex.get('forage.totalDocs', function (err, value) {
    indexSize = value;
  });

  //this must be set to true for a query to be carried out
  var canSearch = true,
  //tq = Transformed Query
      tq = Object.create(q),
      k,
      indexKeys,

self.keywords = function() {
        var keywords = natural.stopwords.filter(function(i) {
            return i.length > 1 || i === "a" || i === "i";
        });

        keywords.push("?");
        keywords.push("when");
        return keywords;
    }();

function Search(key, options) {
    var options = options || {};
    this.key = key;

    this.stopwords=options.stopwords ? options.stopwords : false;
    this.stopwords=options.naturalstop ? natural.stopwords : false;


}