anchor.diff:                           do (format file "~%~4Tpart(~S) = ~A;" p rate-str)
                            finally (format file "~%~4T$c(~A) = ~:[0~;~{part(~A)~^+~}~];" (1+ i) parts parts)))
                     (t (format file "~%~T$c(~A) = ~A;" (1+ i) 
  -                             (rate-str-without-outer-parens rate)))))
  -                  
  -             (scribble (obj pos)
  -               (let ((end (file-position file)))
  -                 (file-position file pos)
  -                 (prin1 obj file)
  -                 (file-position file end))))
  +                             (rate-str-without-outer-parens rate))))))
   
       (format t "~&; Writing model block")
       (format file "MODEL ~A~%~
  
positive.code: ;;;;     (with-dimensionless-math (numerica-model-base-units ci)
  ;;;;       (let ((low-t0     (lowest-non-zero (numerica-model-ode-vars ci) ?.t0))
  ;;;;             (low-kvar   (lowest-non-zero (numerica-model-kvars ci) ?.value)))
  ;;;;         {low-t0 low-kvar}))))
negative.code:   "returns the name of the ...."
    (format nil "~S_k" (carefully-get-filename stream)))
  
  
  ;;;
  ;;; functions for computing default base units
  ;;;
  