text: 'use strict'
  /*global console*/
  
  var thunk = require('../thunks.js')()
  var result = []
  var thunkFn = thunk(1)
  
  function callback (error, value) {
    if (error != null) throw error
    result.push(value)
    return thunk(function (callback2) {
      setTimeout(function () { callback2(null, value * 2) }, 1000)
    })
  }
  console.time('thunk_series')
  for (var i = 0; i < 5; i++) {
    thunkFn = thunkFn(callback)
  }
  thunkFn(function (error) {
    console.log(error, result) // null, [1, 2, 4, 8, 16]
    console.timeEnd('thunk_series') // ~5050ms
  })
  