LotusScript equivalents for the @RightBack

Function RightBack (sourceString As String, searchString As String) As String
'LotusScript equivalents for the @RightBack
For i% = Len(sourceString) To 1 Step -1
sourceStringBack$=sourceStringBack$ & Mid(sourceString, i%, 1)
Next
For i% = Len(searchString) To 1 Step -1
searchStringBack$=searchStringBack$ & Mid(searchString, i%, 1)
Next
pos% = Instr ( sourceStringBack$, searchStringBack$)
If pos% > 0 Then pos% = pos% - 1
result$ = Left ( sourceStringBack$, pos%)
For i% = Len(result$) To 1 Step -1
turn$=turn$ & Mid(result$, i%, 1)
Next
RightBack=turn$
End Function