anchor.diff:                                 if-invalid
                                  parser
                                  completer
  -			       type
  +                               type
                                  (color *prompt-color*)
                                  (error-color *prompt-error-color*))
     "Prompt for a string.
  
positive.code:              for option in options
               for i from 0
               do
                  (format t "[~A] ~A" i option)
                  (when (< (1+ i) (length options))
                    (format t separator)))
             (terpri))
           (read-option ()
             (cond
  
negative.code:                for option in options
                 for i from 0
                 do
                    (format *query-io* "[~A] ~A" i option)
                    (when (< (1+ i) (length options))
                      (format *query-io* separator)))
               (terpri)
               (say "Chosen options: ~{~A~^, ~}" (reverse chosen-options)))
             (read-option ()
  