func (ln *UnixListener) close() error {
	// The operating system doesn't clean up
	// the file that announcing created, so
	// we have to clean it up ourselves.
	// There's a race here--we can't know for
	// sure whether someone else has come along
	// and replaced our socket name already--
	// but this sequence (remove then close)
	// is at least compatible with the auto-remove
	// sequence in ListenUnix. It's only non-Go

	if apierrors.IsAlreadyExists(err) {
		// If we're racing to init and someone else already created it, re-fetch
		return coreClient.ServiceAccounts(namespace).Get(context.TODO(), name, metav1.GetOptions{})
	}
	return sa, err

	}
	return nil
}

// accessReviewResources are resources which give a view into permissions in a namespace.  Users must be allowed to create these
// resources because returning "not found" errors allows someone to search for the "people I'm going to fire in 2017" namespace.
var accessReviewResources = map[schema.GroupResource]bool{
	{Group: "authorization.k8s.io", Resource: "localsubjectaccessreviews"}: true,
}

			// So get off the way.
			if old>>mutexWaiterShift == 0 || old&(mutexLocked|mutexWoken|mutexStarving) != 0 {
				return
			}
			// Grab the right to wake someone.
			new = (old - 1<<mutexWaiterShift) | mutexWoken
			if atomic.CompareAndSwapInt32(&m.state, old, new) {
				runtime_Semrelease(&m.sema, false, 1)
				return
			}
			old = m.state
		}
	} else {

# OpenAPI Callbacks

You could create an API with a *path operation* that could trigger a request to an *external API* created by someone else (probably the same developer that would be *using* your API).

			}
			ec.queue.Add(key)
			break
		}
	}
}

func (ec *ephemeralController) onPVCDelete(obj interface{}) {
	pvc, ok := obj.(*v1.PersistentVolumeClaim)
	if !ok {
		return
	}

	// Someone deleted a PVC, either intentionally or
	// accidentally. If there is a pod referencing it because of
	// an ephemeral volume, then we should re-create the PVC.
	// The common indexer does some prefiltering for us by

# Handling Errors

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

	if v, ok := cache.Load(name); ok {
		return v.(*setting)
	}
	s := new(setting)
	s.info = godebugs.Lookup(name)
	s.value.Store(&empty)
	if v, loaded := cache.LoadOrStore(name, s); loaded {
		// Lost race: someone else created it. Use theirs.
		return v.(*setting)
	}

	return s
}

// setUpdate is provided by package runtime.
// It calls update(def, env), where def is the default GODEBUG setting