A function can be assigned to the dataProvider property in order to set a custom data source.
NOTE: it is responsability of this dataProvider function to execute the callback providing the appropriate
filtered and sorted chunk of items, as well as the total size of the data set.
This example utilises an array as its data storage. The dataProvider function is able to extract
chunks from the array based on the params argument
Listen to save and delete events to persist changes in the database