I'm not familiar with Arcade, but I'm trying to do a simple expression. I need to write an if-else label expression that will label addresses by their address number, unless there is a address unit number; then I would want the label to show the unit number. I've researched this documentation https://developers.arcgis.com/arcade/function-reference/logical_functions/ . I need a statement something like: If address is not Null than populate, or else populate unit number. I'm just not familiar with the Arcade structure.