(defun is_in(el spis)
(cond
((null spis) nil )
((eql el (car spis)) T)
(1 (is_in el (cdr spis)) )
)
)
(defun remove_first(el spis)
(cond
((null spis) nil )
((eql el (car spis)) (cdr spis))
(1 (cons (car spis) ( remove_first el (cdr spis) ) ) )
)
)
(defun group(spis)
(cond
((null spis) nil )
((is_in (car spis) (cdr spis)) (cons (car spis) (group (cons (car spis) (remove_first (car spis) (cdr spis))))))
(1 (cons (car spis) (group (cdr spis))) )
)
)
(PRINT (group '(1 2 1 3 2 5 4 7 4 1)))
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