old_contents: import ActorSystem from './ActorSystem';
  import ActorRef from './ActorRef';
  import Actor from './Actor';
  
  export { ActorSystem, ActorRef, Actor };
  
new_contents: import ActorSystem from './ActorSystem';
  import ActorRef from './ActorRef';
  import Actor from './Actor';
  import WorkerGateway from './WorkerGateway';
  
  export { ActorSystem, ActorRef, Actor, WorkerGateway };
  
subject: add WorkerGateway to the module exports