anchor.diff:    (with-open-file (in pathname)
       (let ((acc))
         (loop :with eof-value := (gensym)
  -        :for form-count :from 0 :by 1
  -        :for x := (read in nil eof-value)
  -        :until (eq x eof-value)
  -        :do (match-search pattern x
  -                          #'(lambda (tree binds footprints)
  -                              (push (make-state :pathname pathname
  -						:form-count form-count
  -						:form tree
  -						:binds binds
  -						:footprints footprints)
  -                                    acc))))
  +	    :for form-count :from 0 :by 1
  +	    :for x := (read in nil eof-value)
  +	    :until (eq x eof-value)
  +	    :do (match-search pattern x
  +			      #'(lambda (tree binds footprints)
  +				  (push (make-search-result
  +					 :pathname pathname
  +					 :form-count form-count
  +					 :form tree
  +					 :binds binds
  +					 :footprints footprints)
  +					acc))))
         (nreverse acc))))
   
   (defun collect-lisp-files ()
  
positive.code: (defpackage clep
    (:use :cl)
    (:export
     :clep-file
     :clep-sexp))
  (in-package :clep)
  
  (defstruct state
    form
    binds
    footprints
  
negative.code:   (let ((acc))
      (match-search pattern x
                    #'(lambda (tree binds footprints)
                        (push (make-search-result :form tree
  						:binds binds
  						:footprints footprints)
  			    acc)))
      (nreverse acc)))
  