code: function (config) {
    var idx = new lunr.Index
  
    idx.pipeline.add(
      lunr.trimmer,
      lunr.stopWordFilter,
      lunr.stemmer
    )
  
    if (config) config.call(idx, idx)
  
    return idx
  }
docs: Convenience function for instantiating a new lunr index and configuring it
  with the default pipeline functions and the passed config function.
  
  When using this convenience function a new index will be created with the
  following functions already in the pipeline:
  
  lunr.StopWordFilter - filters out any stop words before they enter the
  index
  
  lunr.stemmer - stems the tokens before entering the index.
  
  Example:
  
  var idx = lunr(function () {
  this.field('title', 10)
  this.field('tags', 100)
  this.field('body')
  
  this.ref('cid')
  
  this.pipeline.add(function () {
  // some custom pipeline function
  })
  
  })
  
  @param {Function} config A function that will be called with the new instance
  of the lunr.Index as both its context and first parameter. It can be used to
  customize the instance of new lunr.Index.
  @namespace
  @module
  @returns {lunr.Index}