LotusScript equivalents for the @Leftback

Public Function LeftBack(stringToSearch As String, param2 As Variant)
'This is an exact version of @LeftBack() in LotusScript
Const V_INTEGER = 2
Const V_STRING = 8
Const ErrTypeMismatch = 13

Dim v As Variant

If Datatype(param2) = V_INTEGER Then
Let v = Evaluate(|@LeftBack("| & stringToSearch & |"; | & param2 & |)|)
Elseif Datatype(param2) = V_STRING Then
Let v = Evaluate(|@LeftBack("| & stringToSearch & |"; "| & param2 & |")|)
Else
Error(ErrTypeMismatch)
End If

Let leftBack = v(0)

End Function