docs: function handleCompressed(res, _write, _end, unzip, zip, callback) {
    // The rewrite response method is replaced by unzip stream.
    res.write = data => unzip.write(data);
  
    res.end = () => unzip.end();
  
    // Concat the unzip stream.
    let concatWrite = concatStream(data => {
      let body;
      try {
        body = JSON.parse(data.toString());
      } catch (e) {
        body = data.toString();
        console.log('JSON.parse error:', e);
      }
  
      // Custom modified logic
      if (typeof callback === 'function') {
        body = callback(body);
      }
  
      let finish = _body => {
        // Converts the JSON to buffer.
        let body = new Buffer(JSON.stringify(_body));
  
        // Call the response method and recover the content-encoding.
        zip.on('data', chunk => _write.call(res, chunk));
        zip.on('end', () => _end.call(res));
  
        zip.write(body);
        zip.end();
      };
  
      if (body && body.then) {
        body.then(finish);
      } else {
        finish(body);
      }
    });
  
    unzip.pipe(concatWrite);
  }