How to use the read-package-json.extraSet function in read-package-json

pz.on('data', function (data) {
      Object.keys(data).forEach(function (k) {
        if (data[k] !== undefined && data[k] !== null) pkg[k] = data[k]
      })

      // only do a few of these.
      // no need for mans or contributors if they're in the files
      var es = readJson.extraSet
      readJson.extraSet = es.filter(function (fn) {
        return fn.name !== 'authors' && fn.name !== 'mans'
      })
      readJson.extras(packageFile, pkg, function (er, pkg) {
        readJson.extraSet = es
        if (er) return cb(er, pkg)
        pkg = unParsePeople(pkg)
        // no need for the readme now.
        delete pkg.readme
        delete pkg.readmeFilename

        // really don't want to have this lying around in the file
        delete pkg._id

        // ditto
        delete pkg.gitHead

readJson(packageFile, function (er, d) {
    readJson.extraSet = es

    if (er) pkg = {}
    else pkg = d

    ctx.filename = packageFile
    ctx.dirname = path.dirname(packageFile)
    ctx.basename = path.basename(ctx.dirname)
    if (!pkg.version || !semver.valid(pkg.version))
      delete pkg.version

    ctx.package = pkg
    ctx.config = config || {}

    // make sure that the input is valid.
    // if not, use the default
    var pz = new PZ(input, ctx)

readJson(packageFile, function (er, d) {
    readJson.extraSet = es

    if (er) pkg = {}
    else pkg = d

    ctx.filename = packageFile
    ctx.dirname = path.dirname(packageFile)
    ctx.basename = path.basename(ctx.dirname)
    if (!pkg.version || !semver.valid(pkg.version))
      delete pkg.version

    ctx.package = pkg
    ctx.config = config || {}

    // make sure that the input is valid.
    // if not, use the default
    var pz = new PZ(input, ctx)

pz.on('data', function (data) {
      Object.keys(data).forEach(function (k) {
        if (data[k] !== undefined && data[k] !== null) pkg[k] = data[k]
      })

      // only do a few of these.
      // no need for mans or contributors if they're in the files
      var es = readJson.extraSet
      readJson.extraSet = es.filter(function (fn) {
        return fn.name !== 'authors' && fn.name !== 'mans'
      })
      readJson.extras(packageFile, pkg, function (er, pkg) {
        readJson.extraSet = es
        if (er) return cb(er, pkg)
        pkg = unParsePeople(pkg)
        // no need for the readme now.
        delete pkg.readme
        delete pkg.readmeFilename

        // really don't want to have this lying around in the file
        delete pkg._id

        // ditto
        delete pkg.gitHead

pz.on('data', function (data) {
      Object.keys(data).forEach(function (k) {
        if (data[k] !== undefined && data[k] !== null) pkg[k] = data[k]
      })

      // only do a few of these.
      // no need for mans or contributors if they're in the files
      var es = readJson.extraSet
      readJson.extraSet = es.filter(function (fn) {
        return fn.name !== 'authors' && fn.name !== 'mans'
      })
      readJson.extras(packageFile, pkg, function (er, pkg) {
        readJson.extraSet = es
        if (er) return cb(er, pkg)
        pkg = unParsePeople(pkg)
        // no need for the readme now.
        delete pkg.readme
        delete pkg.readmeFilename

        // really don't want to have this lying around in the file
        delete pkg._id

        // ditto
        delete pkg.gitHead

get: function (k) {
        return data[k]
      },
      toJSON: function () {
        return data
      }
    }
  }

  var packageFile = path.resolve(dir, 'package.json')
  input = path.resolve(input)
  var pkg
  var ctx = { yes: yes(config) }

  var es = readJson.extraSet
  readJson.extraSet = es.filter(function (fn) {
    return fn.name !== 'authors' && fn.name !== 'mans'
  })
  readJson(packageFile, function (er, d) {
    readJson.extraSet = es

    if (er) pkg = {}
    else pkg = d

    ctx.filename = packageFile
    ctx.dirname = path.dirname(packageFile)
    ctx.basename = path.basename(ctx.dirname)
    if (!pkg.version || !semver.valid(pkg.version))
      delete pkg.version

    ctx.package = pkg
    ctx.config = config || {}

config = {
      get: function (k) {
        return data[k]
      },
      toJSON: function () {
        return data
      }
    }
  }

  var packageFile = path.resolve(dir, 'package.json')
  input = path.resolve(input)
  var pkg
  var ctx = { yes: yes(config) }

  var es = readJson.extraSet
  readJson.extraSet = es.filter(function (fn) {
    return fn.name !== 'authors' && fn.name !== 'mans'
  })
  readJson(packageFile, function (er, d) {
    readJson.extraSet = es

    if (er) pkg = {}
    else pkg = d

    ctx.filename = packageFile
    ctx.dirname = path.dirname(packageFile)
    ctx.basename = path.basename(ctx.dirname)
    if (!pkg.version || !semver.valid(pkg.version))
      delete pkg.version

    ctx.package = pkg

config = {
      get: function (k) {
        return data[k]
      },
      toJSON: function () {
        return data
      }
    }
  }

  var packageFile = path.resolve(dir, 'package.json')
  input = path.resolve(input)
  var pkg
  var ctx = { yes: yes(config) }

  var es = readJson.extraSet
  readJson.extraSet = es.filter(function (fn) {
    return fn.name !== 'authors' && fn.name !== 'mans'
  })
  readJson(packageFile, function (er, d) {
    readJson.extraSet = es

    if (er) pkg = {}
    else pkg = d

    ctx.filename = packageFile
    ctx.dirname = path.dirname(packageFile)
    ctx.basename = path.basename(ctx.dirname)
    if (!pkg.version || !semver.valid(pkg.version))
      delete pkg.version

    ctx.package = pkg