powerset2 ( allows strings subsets using vecsmall)

powerset2(s)=my(S=Vec(s),b=apply(r->Vec(r),S));for(x=2,#S,b=setbinop((x,y)->if(x!=Vec(y),concat(x,y),concat(x,[])),b,S));b=concat([[]],select(r->r==vecsort(r,,8),b));if(type(s)=="t_VECSMALL",b=apply(r->if(r!=[],r=Strchr(r),r=r),b));b