PETRI/TESTS> (loop for i in '(1 x 2 3 x 4 5 x 6 x 7 x 8)
                   if (eql i 'x)
                     collect list into result 
                     and do (setf list '())
                   else
                     collect i into list 
                   finally (return result))
((1 2 3 4 5 6 7 8) (1 2 3 4 5 6 7 8) (1 2 3 4 5 6 7 8) (1 2 3 4 5 6 7 8)
 (1 2 3 4 5 6 7 8))