anchor.diff:                          (multiple-value-list (realize-gesture-spec :keyboard gesture))))
              (in-table (position gesture keystroke-accelerators :test #'equal)))
         (when (and in-table errorp)
  -        (error 'command-already-present))
  +        (error 'command-already-present :command-table-name
  +               (command-table-designator-as-name table)))
         (if in-table
   	  (setf (nth in-table keystroke-items) item)
   	  (progn
  
positive.code: (defun find-command-table (name &key (errorp t))
    (cond ((command-table-p name) name)
  	((gethash name *command-tables*))
  	(errorp (error 'command-table-not-found))
  	(t nil)))
  
  (define-presentation-method present (object (type command-table) stream
  
negative.code: 		  (setf (cdr accel-tail) (cddr accel-tail))
  		  (setf (cdr items-tail) (cddr items-tail))))
  	    (when errorp
  	      (error 'command-not-present :command-table-name
                       (command-table-designator-as-name table)))))))
    nil)
  
  (defun map-over-command-table-keystrokes (function command-table)
  