code: func handleHook(a HookAction, err error) {
  	if err != nil {
  		// TODO: handle errors
  	}
  
  	switch a {
  	case HookActionContinue:
  		return
  	case HookActionHalt:
  		panic(HookActionHalt)
  	}
  }
docs: // handleHook turns hook actions into panics. This lets you use the
  // panic/recover mechanism in Go as a flow control mechanism for hook
  // actions.