Seminario_TP4_EJ02

(defun agregar (a l)
    (if (null l)
        (cons (list a) l)
        (if (eq a (caar l))
            (append (list (cons a (car l))) (cdr l))
            (cons (car l) (agregar a (cdr l)))
        )
    )
)

(defun agrupar (l &optional (salida nil))
    (if (null l)
        salida
        (if (atom (car l))
            (agrupar (cdr l) (agregar (car l) salida))
            (agrupar (cdr l) (agrupar (car l) salida))
        )
    )
)