Using 'co' with Thunks instead of Promises

co_thunk.js

const co = require('co')

function gen () {
  console.warn('Beginning wait for gen')
  return (callback) => {
    setTimeout( () => {
      console.warn("waiting finished for 'gen'")
      callback(null,7)
    },2000)
  }
}

function gen2 () {
  console.warn('Beginning wait for gen2')
  return (callback) => {
    setTimeout( () => {
      console.warn("waiting finished for 'gen2'")
      callback(null,11)
    },2000)
  }
}

function * main () {
  console.warn('main invoked!')
  let g1 = yield gen()
  console.warn('okay, that was gen')
  let g2 = yield gen2()
  console.warn(`Yay, done! Results are: ${g1} and ${g2}`)
  console.warn('main is finished')
}

co(main)