@example
!SUBSTR(banana, 3) @expansion{} nana
!SUBSTR(banana, 3, 3) @expansion{} nan
-!SUBSTR("banana", 3) @expansion{} @r{error (@code{anana"} is not a valid token)}
+!SUBSTR("banana", 1, 3) @expansion{} @r{error (@code{"ba} is not a valid token)}
!SUBSTR(!UNQUOTE("banana"), 3) @expansion{} nana
!SUBSTR("banana", 3, 3) @expansion{} ana