the arguments in then calls are the returns of the previous ones

then.js

// with each return , the value goes for the next then in chain
// you can chain as many thens as you want, even if you dont return a value

doSomething(args).then(result => {
  return result + 2
}).then(plusTwo => {
  return plusTwo + 2
}).then(plusFour => {
  // and the chain continues as many thens as you want...
}).catch(err => console.log(err))