text: const bottles_on_wall =  n=>{
    switch(n){
      case(0) : return 'No more bottles'; 
      case(1) : return '1 bottle';
      default :  return `${n} bottles`;
    }
  };
  
  const first_sentence = n => `${bottles_on_wall(n)} of beer on the wall, ${bottles_on_wall(n).toLowerCase()} of beer.`;
  
  const second_sentence= n => {
    switch(n){
      case(0) : return 'Go to the store and buy some more, 99 bottles of beer on the wall.'; 
      case(1) : return 'Take it down and pass it around, no more bottles of beer on the wall.';
      case(2) : return 'Take one down and pass it around, 1 bottle of beer on the wall.';
      default :  return `Take one down and pass it around, ${n-1} bottles of beer on the wall.`
    }
  };
  
  
  export class BeerSong {
    static verse(n) {
      return `${first_sentence(n)}\n${second_sentence(n)}\n`;
    }
  
    static sing(begin=99, end=0) {
      let res = '';
      for(let i=end; i<= begin; ++i){
        res = `${BeerSong.verse(i)}\n${res}`;
      }
      return res.slice(0,-1);
    }
  }
  