anchor.diff:  (defstruct print-info
     (pretty-print?  t)
     (downcase?      nil)
  -  (indentation    0))
  +  (indentation    0)
  +  (columns        nil))
   
   (defun %print-gap (str)
     (| (fresh-line? str)
  
positive.code:      ,@body))
  
  (defmacro %with-brackets (str info &body body)
    `(%with-indentation ,str, info
       (princ "(" ,str)
       ,@body
       (princ ")" ,str)))
  
  (defun %print-rest (x str info)
    (when x
  
negative.code:          (%late-print x str info)))))
  
  (defun %print-body (x str info)
    (with-temporary (print-info-indentation info) (+ 1 (car (print-info-columns info)))
      (adolist x
        (fresh-line str)
        (%late-print ! str info))))
  