function* bottlesOfBeer(howMany=99){
  let pluralizeBottles = count => count !== 1 ? "bottles" : "bottle";
  let takeNext = next => next >= 1 ? next.toString() : "No more";
  for (let i = howMany; i >= 0; i--) {
    let bottle = pluralizeBottles(i);
    let bottleNext = pluralizeBottles(i-1);
    let left = takeNext(i);
    let toTake = i > 1 ? "one" : (i == 1 ? "it" : "no more");
    let toTakeNext = takeNext(i-1);
    let line1 = `${left} ${bottle} of beer on the wall, ${left.toLowerCase()} ${bottle} of beer.`;
    let line2 = `\nTake ${toTake} down and pass it around, ${toTakeNext.toLowerCase()} ${bottleNext} of beer on the wall.\n`;
    yield `${line1}${i > 0 ? line2 : ""}`;
  }
  yield `Go to the store and buy some more, ${howMany} bottles of beer on the wall.`;
}

for (let it of bottlesOfBeer()) {
  console.log(it);
}