|fn||function that takes as many arguments as there are lists|
|lists||lists which elements are processed in parallel|
MAPCON applies function FN to the successive cdr of lists. Each application result is DESTRUCTIVELY concatenated into resulting list. In case of FN results that are fresh lists (non-sharing), the result is same as with (APPLY #'APPEND (MAPLIST ...)). See MAPCAR, MAPCAN, MAPCON, MAP, MAPC.
(mapcon (lambda (x) (list 'start x 'end)) '(1 2 3 4)) => (START (1 2 3 4) END START (2 3 4) END START (3 4) END START (4) END)