TL:DR
No box I have tried can handle the line:
List<String>.Add(<String>)
E.g. the Assign box expects my method to return a variable.
I have loaded an Excel file into a dataTable and now I am looping over a column. I want to assign the row values to a list by using strList.Add(row), but the Assign box is not designed to allow that.
Later I will be referring to the strList variable from different places in my state machine. I want to process the first item and then call strList.RemoveAt(0) until all values have been processed and removed.