old_contents: // ------------------------------------
  // #POSTHTML - EXPRESS
  // ------------------------------------
  
  const fs = require('fs')
  const posthtml = require('posthtml')
  
  module.exports = function (path, options, cb) {
    options.extend = options.extend || false
  
    let plugins
  
    if (!options.plugins && options.extend === false) {
      plugins = options.settings['view options'] || []
    } else if (options.extend === true) {
      plugins = options.settings['view options'].concat(options.plugins)
    } else {
      plugins = options.plugins || []
    }
  
    fs.readFile(path, function (err, content) {
      if (err) return cb(new Error(err))
  
      posthtml(plugins)
        .process(content.toString())
        .then(result => cb(null, result.html))
    })
  }
  
new_contents: // ------------------------------------
  // #POSTHTML - EXPRESS
  // ------------------------------------
  
  'use strict'
  
  const fs = require('fs')
  const posthtml = require('posthtml')
  
  exports = module.exports = function (path, options, cb) {
    options.extend = options.extend || false
  
    let plugins
  
    if (!options.plugins && options.extend === false) {
      plugins = options.settings['view options'] || []
    } else if (options.extend === true) {
      plugins = options.settings['view options'].concat(options.plugins)
    } else {
      plugins = options.plugins || []
    }
  
    fs.readFile(path, function (err, content) {
      if (err) return cb(new Error(err))
  
      posthtml(plugins)
        .process(content.toString())
        .then(result => cb(null, result.html))
    })
  }
  
subject: add missing 'use strict' statement