array(string) lesser() - gives back a list of possible xxx's. object xxxs() - gives back a list of possible n's. object xxx(mixed n) - gives back xxx n object xxx(object(Xxx) o) - gives back the corresponing xxx
The list of n's (as returned from xxxs) are always in order.
There are two n's with special meaning, 0 and -1. 0 always gives the first xxx, equal to my_obj->xxx(my_obj->xxxs()), and -1 gives the last, equal to my_obj->xxx(my_obj->xxxs()[-1]).
To get all xxxs in the object, do something like Array.map(my_obj->xxxs(),my_obj->xxx).
xxx(object) may return zero, if there was no correspondning xxx.