# Functions
CatalogSubscriberNamespaces returns the list of namespace (as a map with namespace as key) which has Suscriptions(s) that subscribe(s) to a given CatalogSource (name/namespace).
LabelIndexKeys returns the union of indexed cache keys in the given indexers matching the same labels as the given selector.
MetaLabelIndexFunc returns indicies from the labels of the given object.
PresentCatalogIndexFunc returns index from CatalogSource/CatalogSourceNamespace of the given object (Subscription).
# Constants
MetaLabelIndexFuncKey is the recommended key to use for registering the index func with an indexer.
PresentCatalogIndexFuncKey is the recommended key to use for registering the index func with an indexer.