SPSS - calculate new variable from two string using if-then

I need to develop a statement that will pull string values from two col based on their values and missing values. For example.

• COL-A, COL-B, NEW_VAR
• AA, BB, AA
• ___, CC, CC
• DD, __, DD
• __, __, __

I know this is a simple statement, but I can't seem to figure it out today.