Array Key - macmcmeans/localDataStorage GitHub Wiki
An Array Key is a specific key type whose value is array, and as such is quite handy for managing simple data. Array Keys have dedicated methods that make it easy to add, delete and locate specific elements within the key. This mitigates the need to employ this logic in your code.
The following methods are specific to Array Keys: contains, poke, pull, pullall, push and where.