anchor.diff:  	;; Calculate list of library-versions involved
   	(let ((library-versions-involved
   	       (calculate-library-versions-involved library-version)))
  -
  -	  ;; Validate the library versions list
  -                                        ;(validate-library-versions-list library-versions)
  -
  +	  
   	  (let ((library-versions (pbo-solve-library-versions library-version
   							      library-versions-involved)))
   	    ;; Remove the project library from the library versions list
  
positive.code:                           (:strict (error "Coudn't load ~A" dependency))))))))
     :test #'library-version=))
  
  (defun validate-library-versions-list (versions-list)
    (loop for i from 0 to (1- (length versions-list))
       for vi = (elt versions-list i)
       do
         (loop for j from 1 to (1- (length versions-list))
            for vj = (elt versions-list j)
            when (and (not (equalp i j))
                      (and (equalp (library-name (library vi))
                                   (library-name (library vj)))
                           (and (version vi)
                                (version vj)
                                (not (equalp (version vi)
                                             (version vj))))))
            do (error "Cannot load ~A and ~A" vi vj))))
  
  (defun pick-library-version (library-versions)
    "Picks a version from a library list of versions"
    (let ((library-version (first library-versions)))
  
negative.code: 	(let ((library-versions-involved
  	       (calculate-library-versions-involved library-version)))
  
  	  (let ((library-versions (pbo-solve-library-versions library-version
  							      library-versions-involved)))
  	    ;; Remove the project library from the library versions list
  