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 ~
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 ~