I am not sure if the "extended variants" (allowing 0 or 1 arguments) of
the comparison procedures (string=?, string<?, etc.) were supposed to be
part of the SRFI document, or just part of the implementation.  It seems
like the document still has the non-extended (2 or more arguments)
versions of those procedures while the implementation now has the
extended variants.  Not a major issue in any case, but I thought I'd
point it out in case it's an oversight.