anchor.diff:  (defun load-pick-catalog (module)
     (with-open-file (inf (data-path "pick-catalog.lisp")
                          :if-does-not-exist nil)
  -    (setf (catalog-of module) (if (read inf nil) nil))))
  +    (setf (catalog-of module) (if inf (read inf nil) nil))))
   
   (defmodule pick pick-module ("pick")
     (catalog :accessor catalog-of :initform nil))
  
positive.code: (defun parse-pick-args (raw-args)
    (let (opts args)
      (dolist (arg raw-args)
        (if (string= "-" arg :end2 1)
            (push arg opts)
            (push arg args)))
      (setf args (nreverse args))
      (let* ((addp (find "--add" opts :test #'string=))
             (delp (find "--del" opts :test #'string=))
             (showp (find "--show" opts :test #'string=))
             (category (when (or addp delp showp)
                         (pop args))))
        (values
  
negative.code: 
  (defun find-reference-cycles (catalog start category)
    (dolist (term (lookup-category catalog category))
      (when (or (string-equal start term)
                (find-reference-cycles catalog start term))
        (return t))))
  
  (defun add-pick-choice (module message category choices)
  