for z = (remove-duplicates (intersection (cdr x)(cdr y) :test #'string=))
when z do (error 'simple-program-error
:format-control "Parameters ~S and ~S must be disjoint ~
- but have common elements ~% ~S"
+ but have common elements ~% ~S"
:format-arguments (list (car x)(car y) z)))))
(defun stringify-name (name kind)