I'm new to Python and made a relatively simple expression to base the height of the 2.5D layer buildings off of the number of stories they have and it works as intended, however I have several features that don't have the number of stories and their values are NULL but whenever I try to add the nullif argument after this code:
relation_aggregate(relation:='building', aggregate:='sum',expression:="number_of_str")* 3
it gives me this error
syntax error, unexpected NAME, expecting end of file
What expression can I use to fix my problem?
