code: function concatStreams(array) {
    var concat = new stream.PassThrough();
  
    function pipe(i) {
      if (i < array.length - 1) {
        array[i].pipe(concat, {end: false});
        array[i].on('end', function () { pipe(i + 1) });
      } else {
        array[i].pipe(concat);
      }
    }
    if (array.length > 0) {
      pipe(0);
    }
  
    return concat;
  }
docs: Concatenate an array of streams into a single stream.