(defun find-all (item sequence &rest keyword-args
        &key (test #'eql) test-not &allow-other-keys)
 "Find all those elements of sequence that match item,
 according to the keywords. Doesn't alter sequence."
 (if test-not
  (apply #'remove item sequence
    :test-not (complement test-not) keyword-args)
  (apply #'remove item sequence
    :test (complement test) keyword-args)))