Is there a way to do if/then for properties?

I am adding sourcefile to my properties, but would like to have a conditional statement. If the file contains "_Units" then the file comes from place one

Else Place 2

So far, I have this :

T.Properties.CustomProperties.SourceFile

[Walter Roberson]

contains(T.Properties.CustomProperties.SourceFile, '_Units')

???

[Image Analyst]

if contains(T.Properties.CustomProperties.SourceFile, '_Units', 'IgnoreCase', true)
    % It comes from place one.
    % So do something with that info, like put it into a different column of the table or whatever.
else
    % It comes from place two.
end