mekso operator: power set - produces the set of all subsets of set X1 that are of (any) size (that is) X2 [a nonnegative integer or transfinite/infinite number; default: su'o no].
Possibly also could be used as a nonlogical "connective" of sorts. For accessing more than one cardinality in X2, use modifiers ("less than"/"greater than") or vague numbers; default: "su'o no", which outputs the set of all subsets of X1; thus, the unary operator is just the standard power set operator.