What is your favorite or what you deem most useful function within the PowerApps fx language? Mine is the AddColumns function, because it allows a level of dynamics that would not exist without it. I can create columns and fill data on the fly as my program is running. I can use it to shape data for some chart or report Im creating. I can use it to defeat lookups or filters in galleries or the need to go many levels deep in lookup fields. I can use it to supply mulitple views without using roundtrips to the server. Just think this is the most important THING PowerApps offers apart from the Gallery control.