You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: k8swatcher.go
    path of file: ./repos/juju/caas/kubernetes/provider/watcher
    
    the code of the file until where you have to start completion: // Copyright 2018 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package watcher

import (
	"time"

	jujuclock "github.com/juju/clock"
	"github.com/juju/errors"
	"github.com/juju/loggo"
	"github.com/juju/worker/v3/catacomb"
	"k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/client-go/tools/cache"

	"github.com/juju/juju/core/watcher"
)

var logger = loggo.GetLogger("juju.kubernetes.provider.watcher")

type KubernetesNotifyWatcher interface {
	watcher.CoreWatcher
	Changes() watcher.NotifyChannel
}

// kubernetesNotifyWatcher reports changes to kubernetes
// resources. A native kubernetes watcher is passed
// in to generate change events from the kubernetes
// model. These events are consolidated into a Juju
// notification watcher event.
type kubernetesNotifyWatcher struct {
	clock    jujuclock.Clock
	catacomb catacomb.Catacomb

	out      chan struct{}
	name     string
	informer cache.SharedIndexInformer
}

// NewK8sWatcherFunc defines a function which returns a k8s watcher based on the supplied config.
type NewK8sWatcherFunc func(
	informer cache.SharedIndexInformer,
	name string,
	clock jujuclock.Clock) (KubernetesNotifyWatcher, error)

type WatchEvent string

var (
	WatchEve
    
func (w *kubernetesStringsWatcher) loop() error {
	defer close(w.out)

	select {
	case <-w.catacomb.Dying():
		return w.catacomb.ErrDying()
	case w.out <- w.initialEvents:
	}
	w.initialEvents = nil

	signals := make(chan string)
	fireFn := func(evt WatchEvent) func(interface{}) {
		return func(obj interface{}) {
			meta, err := meta.Accessor(obj)
			if err != nil {
				logger.Errorf("getting kubernetes watcher event meta: %v", err)
			} else {
				logger.Tracef("kubernetes watch event %s %v(%v) = %v", evt,
					meta.GetName(), meta.GetUID(), meta.GetLabels())
			}

			if emittedEvent, ok := w.filterFunc(evt, obj); ok {
				select {
				case signals <- emittedEvent:
				case <-w.catacomb.Dying():
				}
			}
		}
	}

	_, err := w.informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    fireFn(WatchEventAdd),
		DeleteFunc: fireFn(WatchEventDelete),
		UpdateFunc: func(_, obj interface{}) {
			fireFn(WatchEventUpdate)(obj)
		},
	})
	if err != nil {
		return errors.Trace(err)
	}

	// Set out now so that initial event is sent.
	var out chan []string
	var delayCh <-chan time.Time
	var pendingEvents []string

	go w.informer.Run(w.catacomb.Dying())
	for {
		select {
		case <-w.catacomb.Dying():
			return w.catacomb.ErrDying()
		case emittedEvent := <-signals:
			pendingEvents = append(pendingEvents, emittedEvent)
			if delayCh == nil {
				delayCh = w.clock.After(sendDelay)
			}
		case <-delayCh:
			delayCh = nil
			out = w.out
		case out <- pendingEvents:
			out = nil
			pendingEvents = nil
		}
	}
}