anchor.diff:  
   (define-parser arithmetic-up-13-parser
     (consecutive (lambda (var type-spec from form1)
  -		 (declare (ignore from to by))
  +		 (declare (ignore from by))
   		 (make-instance 'for-as-arithmetic
   		   :bindings `((,var ,form1))
   		   :termination nil
  
positive.code: 
  (define-parser arithmetic-up-13-parser
    (consecutive (lambda (var type-spec by form1)
  		 (declare (ignore from to by))
  		 (let ((by-var (gensym)))
  		   (make-instance 'for-as-arithmetic
  		     :bindings `((,var ,0)
  
negative.code: ;;; Order is FROM/UPFROM TO/UPTO BY.
  (define-parser arithmetic-up-1-parser
    (consecutive (lambda (var type-spec from form1 to form2 by form3)
  		 (declare (ignore from by))
  		 (let ((to-var (gensym))
  		       (by-var (gensym)))
  		   (make-instance 'for-as-arithmetic
  		     :bindings `((,var ,form1)
  				 (,to-var ,form2)
  				 (,by-var ,form3))
  		     :termination
  		     `(when (,(if (eq to 'below) '>= '>) ,var ,to-var)
  			(go end))
  		     :step `(incf ,var ,by-var))))
  	       (singleton #'identity
  			  (lambda (x) (and (symbolp x) (not (constantp x)))))
  	       'type-spec-parser
  	       (alternative (keyword-parser 'from)
  			    (keyword-parser 'upfrom))
  	       (singleton #'identity (constantly t))
  	       (alternative (keyword-parser 'to)
  			    (keyword-parser 'upto)
  			    (keyword-parser 'below))
  	       (singleton #'identity (constantly t))
  	       (keyword-parser 'by)
  	       (singleton #'identity (constantly t))))
  