in a FOR loop, by removing the range(x,,)-like double
commas in this case, too, during program compilation.
Previous empty (missing) argument of RANGE was checked
by the terminating comma, but it can be a white space
after it, as in the following example:
FOR i IN RANGE COUNT 'letter' [ PRINT i ]
Reviewed-by: László Németh <firstname.lastname@example.org>