code: function jobDone(err, data) {
          // TODO: check if function was already called before
  
          // check if we close the connection after this (to prevent memory leaks)
          var closing = totalRequests > REQUESTS_BEFORE_WORKER_RESTART ? true : false;
  
          var msg = {};
  
          if (err) {
              msg.errMessage = err.message;
              msg.status = 'fail';
              closing = true; // always close the worker if any error happens
          } else {
              msg.status = 'success';
          }
          msg.data = data;
          msg.closing = closing;
  
          // send our data back to the master
          res.statusCode = 200;
          res.write(JSON.stringify(msg));
          res.close();
  
          // close this worker if necessary
          if (closing) {
              phantom.exit();
          }
      }
docs: job was executed, lets inform the master