anchor.diff:    (let ((acc))
       (match-search pattern x
                     #'(lambda (tree binds footprints)
  -                      (push (make-state :form tree
  -					:binds binds
  -					:footprints footprints)
  +                      (push (make-search-result :form tree
  +						:binds binds
  +						:footprints footprints)
   			    acc)))
       (nreverse acc)))
  
positive.code:   (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))))
        (nreverse acc))))
  
  (defun collect-lisp-files ()
  
negative.code: (defpackage clep
    (:use :cl)
    (:export
     :search-result
     :search-result-p
     :search-result-form
     :search-result-binds
     :search-result-footprints
     :search-result-pathname
     :search-result-form-count
     :clep-file
     :clep-sexp))
  (in-package :clep)
  
  (defstruct search-result
    form
    binds
    footprints
  