code: function Listener(opts) {
    var hash;
  
    Transform.call(this);
    opts = opts || {};
  
    hash = crypto.createHash('sha1', opts.delimiter || 'jambalaya');
    hash.setEncoding('hex');
    hash.end();
  
    this.buffer = new Buffer('');
    this.delimiter = new Buffer('<' + hash.read().substr(0, 10) + '>');
    this.tag_open = false;
  }
docs: main constructor