anchor.diff:  
   (defun read-measurement-from-string (str)
     (declare (type string str)
  -	   #+NIL (values measurement &optional))
  +	   (values measurement &optional))
     (with-input-from-string (s str)
       (read-measurement s)))
   
  
positive.code:     (declare (type simple-string name))
      (case len
        ;; FIXME: Interning arbitrary strings in :KEYWORD creates an
        ;; effective memory leak. Implement
        ;; FIND-MEASUREMENT-CLASS-USING-NAME, and use that function here:
        (1 (values nil (find-measurement-class (intern name '#:keyword))))
        (t (error "PARSER ALGORITHM NOT IMPLEMENTED")) ;; "fail"
        )))
  
  (defun read-measurement (s)
    (declare (type stream s))
    (let ((mag (read s)))
      ;; FIXME: provide CERROR form for ASSERT
      (assert (numberp mag))
  
negative.code: 
  (in-package #:math)
  
  
  (defun read-unit (s)
    (declare (type stream s)
  