Business requirement

A store keeps products that may be available or unavailable. The user needs a button that displays only products currently available for purchase.

1. Create a Product structure with Name and IsAvailable.
2. Prepare a source list containing both available and unavailable products.
3. Create a filtered list variable for the results.
4. When the filter is enabled, loop through the source list and append only items where IsAvailable is True.
5. When the filter is disabled, show all products again.
6. Display the number of visible products above the list.