text: var fs = require('fs');
  var path = require('path');
  var PoolStream = require('../');
  
  var writable = fs.createWriteStream(path.join(__dirname, 'a.mp3'));
  writable.on('finish', function () {
    var readable = fs.createReadStream(path.join(__dirname, 'a.mp3'));
    var pool = new PoolStream();
    var writable = fs.createWriteStream(path.join(__dirname, 'b.mp3'));
  
    readable.pipe(pool).pipe(writable);
  
    // following events will tell you why need pool.
    readable.on('end', function () {
      console.log('readable end time is: %s', new Date());
    });
    pool.on('end', function () {
      console.log('pool end time is: %s', new Date());
    });
    pool.on('finish', function () {
      console.log('pool finish time is: %s', new Date());
    });
    writable.on('finish', function () {
      console.log('writable finish time is: %s', new Date());
    });
  });
  for (var i = 0; i < 10240; i++) {
    writable.write(new Buffer(1024 * 1024));
  }
  writable.end();
  