SOURCE

function assert(value,text) {
    if (value === true) {
        console.log(text)
    } else {
        console.log('error')
    }
} 
function* IdGenerator() {
  let id = 0
  while (true) {
    yield ++id
  }
}

const iterator = IdGenerator()
const ninja1 = {
  id:iterator.next().value
}
const ninja2 = {
  id:iterator.next().value
}
const ninja3 = {
  id:iterator.next().value
}
console.log(ninja1.id)
console.log(ninja2.id)
console.log(ninja3.id)